Updated docs for Yandex TTS

[gipnokote]

Description:
Updated docs for Yandex TTS component.

Pull request in home-assistant (if applicable): home-assistant/core#19603

Checklist:

• Branch: next is for changes and new documentation that will go public with the next home-assistant release. Fixes, changes and adjustments for the current release should be created against current.
• The documentation follows the standards.

[fabaff]

Thanks 🐦

[frenck]

This PR should have been merged into next.

[gipnokote]

I'm sorry, this was my first commit into HA repo, I was reading the dev docs and I wasn't completely sure into which branch I should commit. I decided that if the component already exists then current is the appropriate one. Could you please elaborate the logic how "next" is the proper one, so I know next time where to commit? And should I take any action now?

[frenck]

@gipnokote Sure! If the change matches the current release and thus the current documentation it goes into current. Changes to that branch will be visible live directly after the merge. If the change to the documentation depends on a next release (e.g., new components and features), it should go into the next branch. The next branch will be merged into current on the next Home Assistant release. Causing these change to be visible live on the next release.