Add documentation for daylight, night and twilight duration sensors of the sun integration

[Triple-S]

Proposed change

This is the documentation update corresponding to my proposed change in the core part (home-assistant/core#106936). It simply adds documentation for the proposed 4 new sensors to the sun integration holding the lengths of the day, the night and the twilight at sunrise and sunset.

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 sensors for daylight, night and twilight durations to the sun integration core#106936

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 PR as the parent PR has been closed.