Docs: Add note that you might want Title::getLinkURL

While there are valid use cases of Title::getLocalURL, it is safer
to use Title::getLinkURL in most instances.  Additionally developers
won't accidentally their fragments that way.

Change-Id: I1bf567ba9c38103d39a883e8ea3a60f9f2082181
Merge "Docs: Add note that you might want Title::getLinkURL"