Update Docs for Live Preview to state 3rd Party Dependencies

Problem to Solve

The documentation for Live Preview in the Web IDE does not indicate that even though GitLab is hosting the main packages, there are still calls to 3rd party packages that need to be made.

Proposal

The docs should be updated to make it more clear that by enabling this feature there may be calls to resources outside of the GitLab instance. This will better help administrators make an informed decision about turning this feature on.