Allows the 3 articles that use the same instructions for reviewing
the organization settings to share an include file, and also
allows the 2 articles that share the same settings highlight info
to share an include file as well.
Also, fixes mentions of UI features to use bold instead of
quotations.
Adds content on user group permissions / management to the general
help center article for user groups (`/help/user-groups`) and
removes the then redundant `/help/restrict-user-group-management`
article.
Redirects links in help center and api documentation from deleted
article to the new configure user group settings section of
`/help/user-groups`.
Fixes#21383.
Lauryn Menard
Alya Abbott
Anders Kaseorg
Eeshan Garg