In our new system for updating realm settings, we don't need to create
separate functions to update the input elements for each feature.
Most of the work is done automatically by
`settings_org.sync_realm_settings`.
Update version of Vagrant from 1.8.6 to 2.0.2.
Update version of VirtualBox from 5.1.8 to 5.2.6.
We needed to update Vagrant because older versions have networking
problems on modern Macs, resulting in weird `apt` errors when
provisioning.
Commit message and some text tweaked by tabbott.
This commit helps reduce clutter on the navigation sidebar.
Creates new directories and moves relevant files into them.
Modifies index.rst, symlinks, and image paths accordingly.
This commit also enables expandable/collapsible navigation items,
renames files in docs/development and docs/production,
modifies /tools/test-documentation so that it overrides a theme setting,
Also updates links to other docs, file paths in the codebase that point
to developer documents, and files that should be excluded from lint tests.
Note that this commit does not update direct links to
zulip.readthedocs.io in the codebase; those will be resolved in an
upcoming follow-up commit (it'll be easier to verify all the links
once this is merged and ReadTheDocs is updated).
Fixes#5265.
