Fix documentation for Title::getCascadeProtectionSources and others

The documentation for Title::getCascadeProtectionSources was rendered
nonsensical in r79682, and somehow several following "documentation
cleanup" revisions failed to notice this while cleaning up this same
documentation string.

Fixing that led to fixing Title::getRestrictions and
Title::getAllRestrictions as well.

Change-Id: I48638e370c01fe5ef8ad7d3ebf7fb9aa4385bad7