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/spec/auth/token.md

@@ -1,15 +1,13 @@
 <!--[metadata]>
 +++
-title = "Docker Registry v2 Authentication"
+title = "Token Authentication"
 description = "Introduces the Docker Registry v2 authentication"
-keywords = ["registry, images, repository, v2,  authentication"]
+keywords = ["registry, on-prem, images, tags, repository, distribution, JWT authentication, advanced"]
 [menu.main]
 parent="smn_registry_ref"
 +++
 <![end-metadata]-->
 
-
-
 # Docker Registry v2 authentication via central service
 
 Today a Docker Registry can run in standalone mode in which there are no