Amend keywords section: Add specific rules what should go into keywords

This is intended to start a discussion on amending the KLC keywords section. Proposed change:

Current state:

Reason for proposed change: Review will be more efficient if klc-check tells people like me to remove redundant keywords instead of @kliment1

I intend to add this to klc-check in the future, but better to formalize it first, I think. If no consensus can be reached, we can add it to the extended checks.

@kliment1 Might be interesting to you since it formalizes what you often request in my merge requests.