LED drivers: extract documentation from LED/RGB Matrix pages

[fauxpark]

Description

Proper documentation for each of the supported LED driver ICs, moved out of the LED and RGB Matrix docs, because that's not where it should live.
There might be a few things here or there that I missed or are inconsistent, copy-paste errors etc. which can be tweaked later, but for the most part these are pretty much ready to go.

Types of Changes

• Core
• Bugfix
• New feature
• Enhancement/optimization
• Keyboard (addition or update)
• Keymap/layout/userspace (addition or update)
• Documentation

Issues Fixed or Closed by This PR

Checklist

• My code follows the code style of this project: C, Python
• I have read the PR Checklist document and have made the appropriate changes.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• I have tested the changes and verified that they work and don't break anything (as well as I can manage).

[noroadsleft]

The very tiniest __attribute__ ((weak)) ✔️ because I didn't read every line of every doc, but what I did read was excellent.