Set docker_compose_dir like other inventory vars

When docker-compose become the sole method for using
Docker directly, some of this was shifted around in ways that
are inconsistent with other elements.

This adjusts it so that:

* The inventory variable default is set like the others, and
is less confusing
* We no longer mention the Standalone Docker in inventory
* We format our INSTALL docs w/r/t this var

installer/inventory

@@ -54,11 +54,10 @@ awx_web_hostname=awxweb
 postgres_data_dir=/tmp/pgdocker
 host_port=80
 #ssl_certificate=
+docker_compose_dir=/tmp/awxcompose
 
 # Required for Openshift when building the image on your own
 # Optional for Openshift if using Dockerhub or another prebuilt registry
-# Required for Standalone Docker Install if building the image on your own
-# Optional for Standalone Docker Install if using Dockerhub or another prebuilt registry
 # Required for Docker Compose Install if building the image on your own
 # Optional for Docker Compose Install if using Dockerhub or another prebuilt registry
 # Define if you want the image pushed to a registry. The container definition will also use these images

installer/roles/local_docker/defaults/main.yml

@@ -11,5 +11,3 @@ rabbitmq_password: "guest"
 
 postgresql_version: "9.6"
 postgresql_image: "postgres:{{postgresql_version}}"
-
-docker_compose_dir: "/tmp/awxcompose"