Merge branch 'docs-route-change-redirects' into 'master'

Update docs about changing routes

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/133998



Merged-by: Lukas 'Eipi' Eipert <leipert@gitlab.com>
Approved-by: Lukas 'Eipi' Eipert <leipert@gitlab.com>
Approved-by: Joe Woodward <jwoodward@gitlab.com>
Approved-by: Sean Carroll <scarroll@gitlab.com>
Reviewed-by: Mark Florian <mflorian@gitlab.com>
Co-authored-by: Mark Florian <mflorian@gitlab.com>