Add docs for AirVisual Node/Pro

[bachya]

Proposed change

This PR adds docs for the forthcoming AirVisual PR that adds support for Node/Pro units.

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).
• 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 support for AirVisual Node/Pro units core#32815
• This PR fixes or closes issue: N/A

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.

[frenck]

Closing this PR, since the parent PR has been closed.