Use lower-case for description.

debian/control

@@ -35,7 +35,7 @@ Replaces: lxqt-powermanagement-qt5 (<< 0.9.0)
 Depends:
  ${misc:Depends},
  ${shlibs:Depends},
-Description: Power management module for LXQt
+Description: power management module for LXQt
  The Power management module for LXQt.
  .
  This package contain power management module for LXQt.
@@ -49,7 +49,7 @@ Replaces: lxqt-powermanagement-qt5-dbg (<< 0.9.0)
 Depends:
  ${misc:Depends},
  lxqt-powermanagement (= ${binary:Version}),
-Description: Power management module for LXQt (debug symbols)
+Description: power management module for LXQt (debug symbols)
  The Power management module for LXQt.
  .
  This package contain debugging symbols.