Add app icon

Made by xMasterX!

README.md

@@ -73,3 +73,5 @@ expect to gain any security by using encryption.
 The implementations of AES and GCM are taken directly from
 https://github.com/mko-x/SharedAES-GCM. They were released to the public domain
 by Markus Kosmal.
+
+The app icon was made by @xMasterX.

application.fam

@@ -9,6 +9,7 @@ App(
     ],
     stack_size=8 * 1024,
     fap_category="Sub-GHz",
+    fap_icon="assets/chat_10px.png",
     fap_icon_assets="assets",
     fap_icon_assets_symbol="esubghz_chat",
 )