doc: Fix QObject::connect documentation

doc: Fix QObject::connect documentation

Unfortunately, qdoc is too simple to understand any pointer to member
function syntax.
(the ::* token is not even tokenized. And even if it was, it would be a
difficult way to hack that into the parser. (there is already an ugly
workaround for non-member pointer to function hat works by having '(*'
as a token,but the same hack is not possible for pointer to member function))
So I just put verbatim 'PointerToMemberFunction'

Also remove the obsolete mention that Qt::UniqueConnection is not supported
in that overload. It is now. (And it even contradicts the previous
paragraph)

Change-Id: I8fc9544808c9a462b0f11ccea406e2e33dee15b1
Reviewed-by: Geir Vattekar <geir.vattekar@nokia.com>
Reviewed-by: Casper van Donderen <casper.vandonderen@nokia.com>