Added changelog for version 1.9.1. [skip ci]

Author: jlesage

appdefs.xml

@@ -109,6 +109,11 @@ Where:
     </documentation>
     <!-- Changelog of the application. -->
     <history>
+      <release>
+        <version>1.9.1</version>
+        <date>2020-07-10</date>
+        <change>Improved compatibility by disabling usage of SSE4.2 in OpenResty.</change>
+      </release>
       <release>
         <version>1.9.0</version>
         <date>2020-07-09</date>