added changelog entry

CHANGELOG.md

@@ -3,6 +3,7 @@
 This is a list of high-level changes for each release of AWX. A full list of commits can be found at `https://github.com/ansible/awx/releases/tag/<version>`.
 
 ## 12.0.0 (TBD)
+- Removed memcached as a dependency of AWX (https://github.com/ansible/awx/pull/7240) 
 - Moved to a single container image build instead of separate awx_web and awx_task images. The container image is just `awx` (https://github.com/ansible/awx/pull/7228)
 - Official AWX container image builds now use a two-stage container build process that notably reduces the size of our published images (https://github.com/ansible/awx/pull/7017)
 - Removed support for HipChat notifications ([EoL announcement](https://www.atlassian.com/partnerships/slack/faq#faq-98b17ca3-247f-423b-9a78-70a91681eff0)); all previously-created HipChat notification templates will be deleted due to this removal.

tools/docker-compose-cluster.yml

@@ -104,4 +104,3 @@ services:
   postgres:
     image: postgres:10
     container_name: tools_postgres_1
-

tools/docker-compose.yml

@@ -32,7 +32,6 @@ services:
       - "../:/awx_devel"
       - "../awx/projects/:/var/lib/awx/projects/"
       - "./redis/redis_socket_standalone:/var/run/redis/"
-      - "./rsyslog/:/var/lib/awx/rsyslog"
       - "./docker-compose/supervisor.conf:/etc/supervisord.conf"
     privileged: true
     tty: true