pages/keys: hide XMPP

It became horrible mess including four primary accounts plus two not so
important accounts + two Google accounts, so I am going to pretend XMPP
doesn't exist and manage keys with everyone invidually as needed as
currently I have only one actively XMPP using contact.

The rest moved to Matrix.

pages/keys.markdown

@@ -81,6 +81,7 @@ to communicate with me securely.
     </tr>
 </table>
 
+<!--
 
 ## OMEMO/XMPP
 
@@ -132,6 +133,7 @@ to communicate with me securely.
     </tr>
 </table>
 
+-->
 
 ## OTR
 
@@ -152,7 +154,6 @@ OMEMO instead.
     </tr>
 </table>
 
-
 ## PGP
 
 <table>
@@ -164,7 +165,6 @@ OMEMO instead.
     </tr>
 </table>
 
-
 ## Wire
 
 I have understood that Wire fingerprints don't change by