Added short explanation and units

[csoltenborn]

Proposed change

Weather templates currently can not be created such that they support both Metric and Imperial unit systems (see this comment for details). This PR fixes that problem by requiring certain units for the template values, and by converting them to the appropriate units in the WeatherTemplate class, where information on the configured unit system is available. The required units are added to documentation with this PR.

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: Make sure weather templates work with both Metric and Imperial unit systems core#48641
• 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]

✅ Approved. Can be merged as soon as the parent PR gets merged.

[frenck]

Closing PR as the parent PR has been closed.