Docs/connectors

[PGijsbers]

Change

Further centralizes the different documentation files across the repository into one more structured documentation site.
It should be easier to navigate, find, and present information with the mkdocs plugins and on-page hierarchies.
I generally updated and expanded a lot of information, but in some cases I preferred to withhold since it would be better to improve the docs overtime or to have people more familiar with a particular service write/update the docs.

How to Test

Checklist

• Tests have been added or updated to reflect the changes, or their absence is explicitly explained.
• Documentation has been added or updated to reflect the changes, or their absence is explicitly explained.
• A self-review has been conducted checking:
  • No unintended changes have been committed.
  • The changes in isolation seem reasonable.
  • Anything that may be odd or unintuitive is provided with a GitHub comment explaining it (but consider if this should not be a code comment or in the documentation instead).
• All CI checks pass before pinging a reviewer, or provide an explanation if they do not.

Related Issues