docs: Move more sections under hardware integration

[caksoylar]

Move portions of pages that describe hardware integration parts from feature pages into dedicated pages under Hardware Integration section.

• Defining battery sensing for battery levels
• Underglow and backlight (discussed in docs(feat): further generalize RGB information #2485 (review))
  • I decided to have a Lighting category index page and two subpages. The index page again emphasizes when to use each system
  • Although I added links to pin control page in both pages, this is (for now) a superficial integration and further refactoring to reduce duplication should be done in another PR

PR check-list

• Branch has a clean commit history
• Pre-commit used to check formatting of files, commit messages, etc.

[Nick-Munnich]

I agree that the additional refactoring could be done in a future PR. I think that the config and feature pages ought to also be combined into one. Battery bit LGTM.

[caksoylar]

I think that the config and feature pages ought to also be combined into one.

How do you envision this? I thought it's nice to have all the features' config as reference under configuration. If we move them to e.g. the feature page then the config reference section will be incomplete.

[Nick-Munnich]

I think that the config and feature pages ought to also be combined into one.

How do you envision this? I thought it's nice to have all the features' config as reference under configuration. If we move them to e.g. the feature page then the config reference section will be incomplete.

I was unclear I think: feature pages combined into one and config pages combined into one, making two from four.

[caksoylar]

Got it, yeah that makes sense. Will break quite a few links, and I should remember to add redirects.