Linking for FQN of Classes/Methods does not work

[Girgias]

Visible on the 8.4 migration guide that is live

<classname>\Random\Randomizer</classname> and <methodname>\Random\Randomizer::getBytes</methodname> do not generate links.

[cmb69]

Maybe drop the leading backslashes (for now).

[haszi]

From a cursory look, no linking works with FQNs. This should probably be easy to fix by trimming the leading backslash though. Or so I hope. :-)