Doc topic_template for mqtt.publish

[davidjb]

Proposed change

This documents the addition of the topic_template feature for mqtt.publish from home-assistant/core#53743.

Additionally, this slightly rewords the overlapping, existing documentation on this service in order to explain how payload and payload_template work. The current documentation mentions that payload_template would be ignored if payload were specified, but this isn't the case; voluptuous will raise a schema error as these fields are marked as Exclusive.

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 topic_template for mqtt.publish core#53743
• Link to parent pull request in the Brands repository:
• 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.

[frenck]

Thanks, @davidjb 👍