XEP-0384: clarify wording

xep-0384.xml

@@ -76,9 +76,11 @@
       multi-end to multi-end encryption, allowing messages to be synchronized
       securely across multiple clients, even if some of them are offline. The SignalProtocol
       is a cryptographic double ratched protocol based on work by Trevor Perrin
-      and Moxie Marlinspike first published as the Axolotl protocol. The protocol is not fully
-      documented in public domain and only exists in GPLv3-licensed implementations maintained
-      by OpenWhisperSystems.
+      and Moxie Marlinspike first published as the Axolotl protocol. While the
+      protocol itself has specifications in the public domain, the
+      protobuf-based wire format of the signal protocol is not fully
+      documented. The signal protocol currently only exists in GPLv3-licensed
+      implementations maintained by OpenWhisperSystems.
     </p>
   </section2>
   <section2 topic='Overview' anchor='intro-overview'>