Fix description

Since the description is the same as the package name.
A better description is provided for the user.

Signed-off-by: Vignesh Raman <vignesh.raman@collabora.com>

debian/control

@@ -15,6 +15,6 @@ Standards-Version: 4.4.1
 Package: apertis-hawkbit-agent
 Architecture: any
 Depends: ${shlibs:Depends}, ${misc:Depends}, apertis-update-manager
-Description: Apertis hawkBit agent
- hawkBit agent for Apertis system to check, download and trigger installation
+Description: manage system upgrade from hawkBit update server
+ HawkBit agent for Apertis system to check, download and trigger installation
  of system upgrade from hawkBit update server.