Improve documentation

Add some missing information, fix typos, restructure, and improve
readability

Signed-off-by: Isaac Bennetch <bennetch@gmail.com>

Author: ibennetch

README.md

@@ -1,5 +1,9 @@
 # Official phpMyAdmin Docker image
 
+Note that since phpMyAdmin has been accepted in to the [official DockerHub repository](https://hub.docker.com/_/phpmyadmin), you can use
+either that or this older [phpMyAdmin repository](https://hub.docker.com/r/phpmyadmin/phpmyadmin/) for your Docker installation. This
+is maintained as a courtesy to users who have not migrated.
+
 Run phpMyAdmin with Alpine, Apache and PHP FPM.
 
 [![GitHub CI build status badge](https://github.com/phpmyadmin/docker/workflows/GitHub%20CI/badge.svg)](https://github.com/phpmyadmin/docker/actions?query=workflow%3A%22GitHub+CI%22)
@@ -19,17 +23,15 @@ Run phpMyAdmin with Alpine, Apache and PHP FPM.
 [![Docker Version](https://images.microbadger.com/badges/version/phpmyadmin.svg)](https://microbadger.com/images/phpmyadmin "Get your own version badge on microbadger.com")
 
 
-All following examples will bring you phpMyAdmin on `http://localhost:8080`
+All of the following examples will bring you phpMyAdmin on `http://localhost:8080`
 where you can enjoy your happy MySQL administration.
 
 ## Credentials
 
-phpMyAdmin connects using your MySQL server credentials. Please check the corresponding
-database server image for information on what the default username and password are.
-To modify username and password during installation you can check the corresponding
-database server image on Docker Hub.
+phpMyAdmin connects using your MySQL server credentials. Please check your corresponding
+database server image for information on the default username and password or how to specify your own custom credentials during installation.
 
-The official MySQL and MariaDB use the following environment variables to define these:
+The official MySQL and MariaDB images use the following environment variables to define these:
 
 * `MYSQL_ROOT_PASSWORD` - This variable is mandatory and specifies the password that will be set for the `root` superuser account.
 * `MYSQL_USER`, `MYSQL_PASSWORD` - These variables are optional, used in conjunction to create a new user and to set that user's password.
@@ -41,20 +43,20 @@ The following tags are available:
 * `latest`, `fpm`, and `fpm-alpine` are always the most recent released version
 * Major versions, such as `5`, `5-fpm`, and `5-fpm-alpine`
 * Specific minor versions, such as `5.0`, `5.0-fpm`, and `5-fpm-alpine`
-* Specific patch versions, such as `5.0.0`, `5.0.0-fpm`, and `5.0.0-alpine`
+* Specific patch versions, such as `5.0.0`, `5.0.0-fpm`, and `5.0.0-alpine`.  Note that, on rare occasion, there may be an intermediary "docker-only" release, such as 4.9.2-1
 
-A complete list of tags is [available at Docker Hub](https://hub.docker.com/_/phpmyadmin?tab=tags)
+A complete list of tags is [available at Docker Hub](https://hub.docker.com/r/phpmyadmin/phpmyadmin/tags)
 
 ## Image variants
 
 We provide three variations:
 
 * "apache" includes a full Apache webserver with PHP and includes everything needed to work out of the box.
 This is the default when only a version number is requested.
-* "fpm" only starts a PHP FPM container. Use this variant if you already have a seperate webserver.
+* "fpm" only starts a PHP FPM container. Use this variant if you already have a separate webserver.
 This includes more tools and is therefore a larger image than the "fpm-alpine" variation.
 * "fpm-alpine" has a very small footprint. It is based on Alpine Linux and only starts a PHP FPM process.
-Use this variant if you already have a seperate webserver. If you need more tools that are not available on Alpine Linux, use the fpm image instead.
+Use this variant if you already have a separate webserver. If you need more tools that are not available on Alpine Linux, use the fpm image instead.
 
 ## Usage with linked server
 
@@ -68,29 +70,42 @@ docker run --name myadmin -d --link mysql_db_server:db -p 8080:80 phpmyadmin
 ## Usage with external server
 
 You can specify a MySQL host in the `PMA_HOST` environment variable. You can also
-use `PMA_PORT` to specify port of the server in case it's not the default one:
+use `PMA_PORT` to specify the port of the server in case it's not the default one:
 
 ```sh
 docker run --name myadmin -d -e PMA_HOST=dbhost -p 8080:80 phpmyadmin
 ```
 
 ## Usage with arbitrary server
 
-You can use arbitrary servers by adding ENV variable `PMA_ARBITRARY=1` to the startup command:
+You can use arbitrary servers by adding the environment variable `PMA_ARBITRARY=1` to the startup command:
 
 ```sh
 docker run --name myadmin -d -e PMA_ARBITRARY=1 -p 8080:80 phpmyadmin
 ```
 
 ## Usage with docker-compose and arbitrary server
 
-This will run phpMyAdmin with arbitrary server - allowing you to specify MySQL/MariaDB
-server on login page.
-
-Using the docker-compose.yml from https://github.com/phpmyadmin/docker
+This will run phpMyAdmin with the arbitrary server option - allowing you to specify any MySQL/MariaDB
+server on the login page.
 
 ```sh
-docker-compose up -d
+version: '3.1'
+
+services:
+  db:
+    image: mariadb:10.3
+    restart: always
+    environment:
+      MYSQL_ROOT_PASSWORD: notSecureChangeMe
+
+  phpmyadmin:
+    image: phpmyadmin
+    restart: always
+    ports:
+      - 8080:80
+    environment:
+      - PMA_ARBITRARY=1
 ```
 
 ## Run the E2E tests with docker-compose
@@ -106,24 +121,25 @@ docker-compose -f docker-compose.testing.yml up phpmyadmin
 ## Adding Custom Configuration
 
 You can add your own custom config.inc.php settings (such as Configuration Storage setup)
- by creating a file named "config.user.inc.php" with the various user defined settings
+ by creating a file named `config.user.inc.php` with the various user defined settings
 in it, and then linking it into the container using:
 
 ```sh
 -v /some/local/directory/config.user.inc.php:/etc/phpmyadmin/config.user.inc.php
 ```
 
-On the "docker run" line like this:
+On the `docker run` line like this:
 
 ```sh
 docker run --name myadmin -d --link mysql_db_server:db -p 8080:80 -v /some/local/directory/config.user.inc.php:/etc/phpmyadmin/config.user.inc.php phpmyadmin
 ```
 
-See the following links for config file information.
-https://docs.phpmyadmin.net/en/latest/config.html#config
-https://docs.phpmyadmin.net/en/latest/setup.html
+See the following links for config file information:
+
+* https://docs.phpmyadmin.net/en/latest/config.html#config
+* https://docs.phpmyadmin.net/en/latest/setup.html
 
-## Usage behind reverse proxys
+## Usage behind a reverse proxy
 
 Set the variable ``PMA_ABSOLUTE_URI`` to the fully-qualified path (``https://pma.example.net/``) where the reverse proxy makes phpMyAdmin available.
 
@@ -136,11 +152,10 @@ Set the variable ``PMA_ABSOLUTE_URI`` to the fully-qualified path (``https://pma
 * ``PMA_HOSTS`` - define comma separated list of address/host names of the MySQL servers
 * ``PMA_VERBOSES`` - define comma separated list of verbose names of the MySQL servers
 * ``PMA_PORTS`` -  define comma separated list of ports of the MySQL servers
-* ``PMA_USER`` and ``PMA_PASSWORD`` - define username to use for config authentication method
-* ``PMA_ABSOLUTE_URI`` - define user-facing URI
+* ``PMA_USER`` and ``PMA_PASSWORD`` - define username and password to use only with the `config` authentication method
+* ``PMA_ABSOLUTE_URI`` - the full URL to phpMyAdmin. Sometimes needed when used in a reverse-proxy configuration. Don't set this unless needed. See [documentation](https://docs.phpmyadmin.net/en/latest/config.html#cfg_PmaAbsoluteUri).
 * ``PMA_CONFIG_BASE64`` - if set, this option will override the default `config.inc.php` with the base64 decoded contents of the variable
 * ``PMA_USER_CONFIG_BASE64`` - if set, this option will override the default `config.user.inc.php` with the base64 decoded contents of the variable
-* ``PMA_ABSOLUTE_URI`` - the full URL to phpMyAdmin. Sometimes needed when used in a reverse-proxy configuration. Don't set this unless needed. See [documentation](https://docs.phpmyadmin.net/en/latest/config.html#cfg_PmaAbsoluteUri).
 * ``PMA_CONTROLHOST`` - when set, this points to an alternate database host used for storing the [phpMyAdmin Configuration Storage database](https://docs.phpmyadmin.net/en/latest/setup.html#phpmyadmin-configuration-storage) database
 * ``PMA_CONTROLPORT`` - if set, will override the default port (3306) for connecting to the control host for storing the [phpMyAdmin Configuration Storage database](https://docs.phpmyadmin.net/en/latest/setup.html#phpmyadmin-configuration-storage) database
 * ``PMA_PMADB`` - define the name of the database to be used for the [phpMyAdmin Configuration Storage database](https://docs.phpmyadmin.net/en/latest/setup.html#phpmyadmin-configuration-storage). When not set, the advanced features are not enabled by default (they can still potentially be enabled by the user when logging in with the zero conf (zero configuration) feature. Suggested values: `phpmyadmin` or `pmadb`