web apps app improve description to close #544

apps/Web Apps/description

@@ -1 +1,7 @@
-Linux Mint's official Web Apps program.
+Run websites as if they were apps.
+This is Linux Mint's official Web Apps program. Using it, you can run any website as a standalone app.
+
+If there are multiple browsers installed on the system, Web Apps will let you choose which one to use. It also lets you select an icon, menu category, and text label. When finished, a new button will appear in the main menu.
+
+To run: Menu -> Internet -> Web Apps
+To run in a terminal: webapp-manager