Documentation enhancements

Making metadata:
- more consistent
- more specific (fixed copy pasting)
- refine coverage

Insecure information cleanup

Removing no longer used files:
- mkdocs is gone
- the registry diagram is not used, and is a bit silly :)

Minor fixes

Fixing links

Recipes:
- harmonized code sections style to the rest of the docs
- harmonized recipe "style"
- listing new recipes

Enhance deploying

Signed-off-by: Olivier Gambier <olivier@docker.com>

docs/recipes.md

@@ -1,8 +1,8 @@
 <!--[metadata]>
 +++
-title = "Recipes for Registry"
+title = "Recipes"
 description = "Fun stuff to do with your registry"
-keywords = ["registry, service, images, repository, recipe"]
+keywords = ["registry, on-prem, images, tags, repository, distribution, recipes, advanced"]
 +++
 <![end-metadata]-->
 
@@ -30,3 +30,5 @@ At this point, it's assumed that:
 
  * [using Apache as an authenticating proxy](apache.md)
  * [using Nginx as an authenticating proxy](nginx.md)
+ * [running a Registry on OSX](osx-setup-guide.md)
+ * [hacking the registry: build instructions](building.md)