Change translation rule 6

[oyvindwe]

Proposed change

Change translation rule 6 to not build translation strings based on other keys. This is an anti-pattern, as usages of a string is may not be reviewed. hassfest also disallows this in strings.json.

Type of change

• Document existing features within Home Assistant
• Document new or changing features which there is an existing pull request elsewhere
• Spelling or grammatical corrections, or rewording for improved clarity
• Changes to the backend of this documentation
• Removed stale or deprecated documentation

Additional information

• This PR fixes or closes issue: fixes #
• Link to relevant existing code or pull request: