Updates help center, integration and contributor docs where for
the new subsections on the organization settings tab, which were
changed in #33605.
Previously, these settings were all in the "Other settings"
subsection for that organization settings tab.
We had a mix of the two names, and "video call provider" both feels
more professional and more clear about precisely what it does.
We don't change the API fields, since it doesn't seem worth an API
migration.
Moves documentation about using zoom as video call provider
to /integrations. This documentation was earlier present
at /help/start-a-call and is moved as asked in issue #17588.
