My preference would be BitBucket (slightly simpler than github and allows for free private repositories), but, either way, the result is the same: fewer steps to updating the manual. Moving away from svn to git is also a step in the right direction, IMO.

One aspect of wikis that I thoroughly enjoy is the ability to fix something (contribute) immediately. Moving to a web-based repository for the manual removes barriers (such as waiting upon moderated approvals whilst the moderator vacations) to letting people contribute to projects. Throw in a nightly build (with blaming) to ensure that the manual compile is never broken (for long).

Regards.