Add recent contributors to credits

OpenPGP-Keychain/src/main/res/raw/help_about.html

@@ -15,6 +15,12 @@ And don't add newlines before or after p tags because of transifex -->
 <li>Ash Hughes (crypto patches)</li>
 <li>Brian C. Barnes</li>
 <li>Bahtiar 'kalkin' Gadimov (UI)</li>
+<li>Daniel Hammann</li>
+<li>Daniel Haß</li>
+<li>Greg Witczak</li>
+<li>Miroojin Bakshi</li>
+<li>Paul Sarbinowski</li>
+<li>Vincent Breitmoser</li>
 
 </ul>
 <h2>Developers APG 1.x</h2>