Updating .desktop file. Make it match registered categories to avoid lintian warns.

debian/patches/desktop-category.patch

@@ -0,0 +1,11 @@
+--- a/resources/lxqt-about.desktop.in
++++ b/resources/lxqt-about.desktop.in
+@@ -5,7 +5,7 @@
+ Comment=Learn more about LXQt
+ Exec=lxqt-about
+ Icon=help-about
+-Categories=Help;LXQt
++Categories=System;Documentation
+ OnlyShowIn=LXQt;LXDE;
+ 
+ #TRANSLATIONS_DIR=translations

debian/patches/series

@@ -0,0 +1 @@
+desktop-category.patch