Merge branch 'md-customize-terminal-docs' into 'main'

Add instructions to customize GDKiab terminal with branch name

See merge request https://gitlab.com/gitlab-org/gitlab-development-kit/-/merge_requests/3600



Merged-by: Lee Tickett <ltickett@gitlab.com>
Approved-by: Lee Tickett <ltickett@gitlab.com>
Reviewed-by: Lee Tickett <ltickett@gitlab.com>
Co-authored-by: Missy Davies <mdavies@gitlab.com>