Issue forms should only reference labels that exist in the repository so
new reports receive the intended automatic labels.
This updates the CLI issue form to stop applying the missing `needs
triage` label, and changes the documentation issue form from `docs` to
the existing `documentation` label.
Fixes#21158
Fixes#21270.
The CLI bug report template defined `description` twice for the terminal
emulator field. Because duplicate YAML keys are ambiguous and parsers
generally keep the later value, the form could drop the multiplexer
guidance.
This combines that guidance with the terminal examples under a single
block scalar in `.github/ISSUE_TEMPLATE/3-cli.yml`.
