add ssr to keywords

Author: Ashark

data/simplescreenrecorder.desktop

@@ -9,4 +9,4 @@ Icon=simplescreenrecorder
 Exec=simplescreenrecorder --logfile
 Terminal=false
 Categories=AudioVideo;Video;Recorder;Qt;
-Keywords=screen recorder;screencast;live streaming;
+Keywords=screen recorder;screencast;live streaming;ssr;