Clarify YAML reloading config header

[balloob]

Breaking change

Proposed change

So both person and zone would crash if you didn't have person/zones in your YAML and called the reload service. Both times it was reported by someone who did not use YAML to config either but somehow thought they had to call the reload functions.

This PR clarifies header/description. Suggestons on improvements for this welcome.

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New feature (thank you!)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Example configuration

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue:
• Link to documentation pull request:

Checklist

• The code change is tested and works locally.
• There is no commented out code in this PR.
• Tests have been added to verify that the new code works.

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated for www.home-assistant.io