Added app descriptions (#8)

application.fam

@@ -1,6 +1,7 @@
 App(
     appid="avr_isp",
     name="AVR Flasher",
+    description="Application for flashing AVR microcontrollers",
     apptype=FlipperAppType.EXTERNAL,
     entry_point="avr_isp_app",
     requires=["gui"],