Add documentation for ws66i core integration

[ssaenger]

Proposed change

This is the documentation for the ws66i core integration.

Type of change

• Spelling, grammar or other readability improvements (current branch).
• Adjusted missing or incorrect information in the current documentation (current branch).
• Added documentation for a new integration I'm adding to Home Assistant (next branch).
  • I've opened up a PR to add logo's and icons in Brands repository.
• Added documentation for a new feature I'm adding to Home Assistant (next branch).
• Removed stale or deprecated documentation.

Additional information

• Link to parent pull request in the codebase: Add ws66i core integration core#56094
• Link to parent pull request in the Brands repository: Add images for ws66i core integration brands#2809
• This PR fixes or closes issue:

Checklist

• This PR uses the correct branch, based on one of the following:
  • I made a change to the existing documentation and used the current branch.
  • I made a change that is related to an upcoming version of Home Assistant and used the next branch.
• The documentation follows the Home Assistant documentation standards.

[ssaenger]

Comment to keep PR from going stale.

[ssaenger]

@frenck Is it appropriate to contact the vendor of the amplifier and ask for a discount code to be displayed on the documentation page?

[frenck]

@ssaenger I would say: No.

[frenck]

We have scenes that provide this functionality in Home Assistant, why does this integration provide its own logic for this?

[ssaenger]

@frenck Done. Custom services were removed in home-assistant/core#71717

[frenck]

Thanks, @ssaenger 👍