Add Guides section to provider docs

[matifali]

We document use cases for provider resources within each resource and data block. It would be nice to document some specific uses as Guides in a separate section.
An example is guides on JFrog Artifactory Provider.

A few suggestions I have are:

1. How to manage staging template versions for a template. (available under coderd_template)
2. How to set up a workspace proxy (available under coderd_workspace_proxy)

We already have these in our docs under respective resources. It just needs a bit of refactoring to expose them as Guides and rewrite them if needed.

[bpmct]

Nice! Managing organizations and group sync would be a good one when #39 is complete