XEP-0434: Release version 0.5.1

Update to XEP-0450 version 0.3.0 and apply consistent formatting:

* Update ATM's namespace to 'urn:xmpp:atm:1'
* Apply consistent formatting for revision history

xep-0434.xml

@@ -2,7 +2,7 @@
 <!DOCTYPE xep SYSTEM 'xep.dtd' [
 	<!ENTITY % ents SYSTEM 'xep.ent'>
 	<!ENTITY ns "urn:xmpp:tm:0">
-	<!ENTITY ns-atm "urn:xmpp:atm:0">
+	<!ENTITY ns-atm "urn:xmpp:atm:1">
 	<!ENTITY ns-omemo "urn:xmpp:omemo:1">
 	<!ENTITY ns-sce "urn:xmpp:sce:1">
 %ents;
@@ -36,6 +36,18 @@
 		<email>melvo@olomono.de</email>
 		<jid>melvo@olomono.de</jid>
 	</author>
+	<revision>
+		<version>0.5.1</version>
+		<date>2021-05-14</date>
+		<initials>melvo</initials>
+		<remark>
+			<p>Update to XEP-0450 version 0.3.0 and apply consistent formatting:</p>
+			<ul>
+				<li>Update ATM's namespace to 'urn:xmpp:atm:1'</li>
+				<li>Apply consistent formatting for revision history</li>
+			</ul>
+		</remark>
+	</revision>
 	<revision>
 		<version>0.5.0</version>
 		<date>2021-04-16</date>
@@ -106,7 +118,7 @@
 		<version>0.0.1</version>
 		<date>2020-02-15</date>
 		<initials>melvo</initials>
-		<remark><p>First draft</p></remark>
+		<remark>First draft</remark>
 	</revision>
 </header>
 <section1 topic='Introduction' anchor='introduction'>