Change app type to EXTERNAL and update build instruction.

README.md

@@ -9,6 +9,6 @@ Hit any button other than back repeatedly. Calculates based on the average of th
 ## Compiling
 
 ```
-./fbt firmware_bpm_tapper
+./fbt fap_bpm_tapper
 ```
 

application.fam

@@ -1,7 +1,7 @@
 App(
     appid="bpm_tapper",
     name="BPM Tapper",
-    apptype=FlipperAppType.PLUGIN,
+    apptype=FlipperAppType.EXTERNAL,
     entry_point="bpm_tapper_app",
     cdefines=["APP_BPM_TAPPER"],
     requires=["gui"],