clarify OpenPGP data handling in "about"

The term "technical data" bothered me, since all of the identity information (including e-mail addresses!) are technical data too.

The "up- and downloaded on" construction was not only awkward, it was incorrect: the policies for what can be uploaded differ from the policies of what will be downloaded. Separating out what will be stored and retransmitted seems better.

The last "However," statement wasn't really a "however" -- it's one of the main reasons for the keyserver to exist! I've made it a bit stronger.