[add_note_about_filled_buttons] add note and example for filled button

[scherler]

Added example for filled button

Testing done

Submitter checklist

• Make sure you are opening from a topic/feature/bugfix branch (right side) and not your main branch!
• Ensure that the pull request title represents the desired changelog entry
• Please describe what you did
• Link to relevant issues in GitHub or Jira
• Link to relevant pull requests, esp. upstream and downstream changes
• Ensure you have provided tests - that demonstrates feature works or fixes the issue

[timja]

(conflicts)

[janfaracik]

Heya. Any thoughts on #370 instead? Just a small change compared to yours but I think it gives an example of when you might use said modifiers, e.g. for building or deleting.

[scherler]

@janfaracik left a comment there