Docs: add context and links to documented features (#1477)

* docs(add-to-your-site): include verbose document links

- add extra references to config.yml

* docs(collection-types): provide consistent examples

- include link to configuration doc
- describe admin UI behaviour when accessing files

* docs(add-to-your-site): make authentication phrasing less biased

- add note regarding core behaviour fetching remote files

* docs(collection-types): add note about configurable branches

* docs(website): add more descriptive language to configuration notes

- include deep links to documentation where applicable

* docs(website): change link titles to match their target content

website/content/docs/configuration-options.md

@@ -24,6 +24,8 @@ _This setting is required._
 
 The `backend` option specifies how to access the content for your site, including authentication. Full details and code samples can be found in [Authentication & Backends](https://www.netlifycms.org/docs/authentication-backends).
 
+**Note**: no matter where you access Netlify CMS — whether running locally, in a staging environment, or in your published site — it will always fetch and commit files in your hosted repository (for example, on GitHub), on the branch you configured in your Netlify CMS config.yml file. This means that content fetched in the admin UI will match the content in the repository, which may be different from your locally running site. It also means that content saved using the admin UI will save directly to the hosted repository, even if you're running the UI locally or in staging.
+
 ## Publish Mode
 
 By default, all entries created or edited in the Netlify CMS are committed directly into the main repository branch.