Improve docs for MQTT state vacuum state_topic and value_template.

[emontnemery]

Proposed change

Improve docs for MQTT state vacuum state_topic and remove documentation of value_template which is not working and has been removed (home-assistant/core#33536).

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

• Related to core PR Remove MQTT state vacuum value_template support. core#33536

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]

Thanks, @emontnemery 👍