Recommend plugin bom, remove old changelog

Link to the old changelog with a tag based on the release after the last
release that used the changelog.  Note the date range of the changelog
in the text so that readers do not waste time following the link to see
how old it is.

Author: MarkEWaite

CHANGELOG.md

@@ -9,6 +9,7 @@ It allows managing library updates independently from plugins.
 ### Plugins directly depending on httpclient
 
 Replace the dependency to `org.apache.httpcomponents:httpclient` with the dependency to `apache-httpcomponents-client-4-api`.
+To avoid version conflicts it is suggested not to depend on a specific version, but use the [Jenkins plugin BOM](https://github.com/jenkinsci/bom#readme).
 
 * Before:
     ```
@@ -29,7 +30,6 @@ Replace the dependency to `org.apache.httpcomponents:httpclient` with the depend
       <dependency>
         <groupId>org.jenkins-ci.plugins</groupId>
         <artifactId>apache-httpcomponents-client-4-api</artifactId>
-        <version>4.5.10-1.0</version>
       </dependency>
       ...
     </dependencies>
@@ -38,6 +38,7 @@ Replace the dependency to `org.apache.httpcomponents:httpclient` with the depend
 ### Plugins using libraries depending on httpclient
 
 Add the dependency to `apache-httpcomponents-client-4-api` BEFORE any of dependencies to those libraries to force maven to use `httpclient` declared by `apache-httpcomponents-client-4-api`.
+To avoid version conflicts it is suggested not to depend on a specific version, but use the [Jenkins plugin BOM](https://github.com/jenkinsci/bom#readme).
 
 * Before:
     ```
@@ -61,7 +62,6 @@ Add the dependency to `apache-httpcomponents-client-4-api` BEFORE any of depende
       <dependency>
         <groupId>org.jenkins-ci.plugins</groupId>
         <artifactId>apache-httpcomponents-client-4-api</artifactId>
-        <version>4.5.10-1.0</version>
       </dependency>
       <dependency>
         <artifactId>somelibrary-using-httpclient</artifactId>
@@ -77,7 +77,8 @@ Add the dependency to `apache-httpcomponents-client-4-api` BEFORE any of depende
 
 ## Release Notes
 
-See the [Changelog](CHANGELOG.md).
+Current release notes are on [GitHub releases](https://github.com/jenkinsci/apache-httpcomponents-client-4-api-plugin/releases).
+See the archived [Changelog](https://github.com/jenkinsci/apache-httpcomponents-client-4-api-plugin/blob/apache-httpcomponents-client-4-api-4.5.5-2.0/CHANGELOG.md) for releases before 2019.
 
 ## License