Major update of the API documentation (#1557)

* Add initial HID API documentation

The first version has placeholders for responses, to be filled at a later time.

* Add initial Streamer API documentation

Currently missing information about query parameters and a few others things.
To be fixed after the first pass at all APIs.

* Add initial PiKVM Switch API and Redfish API documentation

This covers the basics and requires some testing to finalize the documentation

* Cleanup, part 1 of N

- Write short intro for HID and Streamer sections
- Fix the structure in HI and Streamer
- Standardize descriptions

* Cleanup, part 2 of N: more standardization

* Cleanup, part 3 of N:

- Standardize the markup for code blocks and CLI commands
- Enable the 'copy code' button in the theme

* Cleanup, part 4 of N:

- Actually commit the theme settings change (copy code button)
- Wrap URLs with ampersands in single quotes as requested by @mdevaev
- Clarify a few points as suggested by @mdevaev

* Cleanup, part 5 of N:

- Update MSD and GPIO docs for consistence's sake
- A bunch of FIXMEs to take care of alt a later time

* GPIO API: mention the pulse mode support requirement

* Cleanup Responses subsections, we'll do it differently

* Update API documentation: OCR options and examples, GPIO, and more

mkdocs.yml

@@ -36,6 +36,7 @@ theme:
         - search.highlight
         - search.share
         - search.suggest
+        - content.code.copy
 
 extra_css:
     - _assets/user.css