Cleanup doc reference links.

Removed 'Compose command line completion' and 'Compose environment variables' from the list. command line completion is linked to from install docs, and environment variables are deprecated.

Signed-off-by: Daniel Nephin <dnephin@docker.com>

docs/index.md

@@ -55,8 +55,6 @@ Compose has commands for managing the whole lifecycle of your application:
 - [Get started with WordPress](wordpress.md)
 - [Command line reference](/reference)
 - [Yaml file reference](yml.md)
-- [Compose environment variables](env.md)
-- [Compose command line completion](completion.md)
 
 ## Quick start
 
@@ -218,14 +216,3 @@ like-minded individuals, we have a number of open channels for communication.
 * To contribute code or documentation changes: please submit a [pull request on Github](https://github.com/docker/compose/pulls).
 
 For more information and resources, please visit the [Getting Help project page](https://docs.docker.com/project/get-help/).
-
-## Where to go next
-
-- [Installing Compose](install.md)
-- [Get started with Django](django.md)
-- [Get started with Rails](rails.md)
-- [Get started with WordPress](wordpress.md)
-- [Command line reference](/reference)
-- [Yaml file reference](yml.md)
-- [Compose environment variables](env.md)
-- [Compose command line completion](completion.md)