[ci skip] Add notice for Redis 4.0 requirement, update examples

Author: lae

README.adoc

@@ -84,6 +84,10 @@ install `redis-server` via a task in `pre_tasks` within your playbook or use a
 Redis installation role such as
 https://galaxy.ansible.com/davidwittman/redis[DavidWittman.redis].
 
+WARNING: NetBox v2.9.0+ require Redis 4.0 at the minimum. The role suggested
+above defaults to a 2.8 version, so make sure you specify a newer version in a
+role variable or deploy Redis 4.0+ another way.
+
 == Role Variables
 
 TIP: See `examples/` for some playbooks you could write for different scenarios.
@@ -417,6 +421,8 @@ socket to talk to the Postgres server with the default netbox database user.
       - name: "{{ netbox_database_user }}"
         role_attr_flags: CREATEDB,NOSUPERUSER
     redis_bind: 127.0.0.1
+    redis_version: 6.0.9
+    redis_checksum: sha256:dc2bdcf81c620e9f09cfd12e85d3bc631c897b2db7a55218fd8a65eaa37f86dd
 ----
 
 Note the `CREATEDB` attribute.
@@ -448,6 +454,8 @@ installing NetBox on to authenticate with it over TCP:
     netbox_database_user: netbox_prod_user
     netbox_database_password: "very_secure_password_for_prod"
     redis_bind: 127.0.0.1
+    redis_version: 6.0.9
+    redis_checksum: sha256:dc2bdcf81c620e9f09cfd12e85d3bc631c897b2db7a55218fd8a65eaa37f86dd
 ----
 
 See the `examples/` directory for more.

examples/playbook_single_host_deploy.yml

@@ -24,6 +24,8 @@
       - name: "{{ netbox_database_user }}"
         role_attr_flags: CREATEDB,NOSUPERUSER
     redis_bind: 127.0.0.1
+    redis_version: 6.0.9
+    redis_checksum: sha256:dc2bdcf81c620e9f09cfd12e85d3bc631c897b2db7a55218fd8a65eaa37f86dd
   pre_tasks:
     - name: Enable Subscription Manager Repos
       rhsm_repository: