Added changelog for version 1.13.0. [skip ci]

Author: jlesage

appdefs.xml

@@ -136,6 +136,11 @@ section for more details.
   </documentation>
   <!-- Changelog of the application. -->
   <history>
+      <release>
+        <version>1.13.0</version>
+        <date>2019-12-03</date>
+        <change>Upgraded MakeMKV to version 1.14.6.</change>
+      </release>
       <release>
         <version>1.12.3</version>
         <date>2019-10-03</date>