Update appdata file for the upcoming release (changes+versionnumber).

data/io.github.wxmaxima_developers.wxMaxima.appdata.xml

@@ -57,7 +57,31 @@
     <content_attribute id="social-info">mild</content_attribute>
   </content_rating>
   <releases>
-   <release version="21.05.2" date="2021-05-20T07:04:00Z">
+   <release version="21.11.0" date="2021-11-21T18:00:00Z">
+     <description>
+	<p>
+       Many bug fixes and improvements.
+    <ul>
+<li>Allow seeing all files in the file save dialog. (#1557)</li>
+<li>Fix an error when using Alt up arrow (show previous command) (#1566)</li>
+<li>Rewrote a config dialogue</li>
+<li>Improvements in the manual</li>
+<li>Update Spanish translation of manual</li>
+<li>Update German, Russian, Hungarian and Ukrainian translation</li>
+<li>Fix a warning, which occurred, when starting wxMaxima the first time</li>
+<li>ww898 unnecessarily limited the list of supported platforms</li>
+<li>wxMaxima's properties to Maxima symbols can now no more be killed</li>
+<li>Allow single GroupCells to be converted to LaTeX</li>
+<li>Enable reloading and changing images inserted via "Cell" -&gt; "Insert Image..." (#1597)</li>
+<li>Correctly set the document saved state when the size of an image is changed</li>
+<li>Use the AUTHORS file for the Credits page in the "About" dialogue</li>
+<li>Handle power events (#1607)</li>
+<li>Fix ugly buttons in the sidebars with recent wxWidgets</li>
+</ul>
+	</p>
+      </description>
+  </release>
+  <release version="21.05.2" date="2021-05-20T07:04:00Z">
       <description>
 	<p>
 	  The integral signs weren't visible or were misplaced on some MS Windows