Update FVM config files

.fvm/fvm_config.json

@@ -1,4 +0,0 @@
-{
-  "flutterSdkVersion": "beta",
-  "flavors": {}
-}

.fvmrc

@@ -0,0 +1,4 @@
+{
+  "flutter": "beta",
+  "flavors": {}
+}

.gitignore

@@ -35,4 +35,6 @@ doc/api/
 *.ipr
 *.iws
 .idea/
-.fvm/flutter_sdk
+
+# FVM Version Cache
+.fvm/

docs/setting_dev_env.md

@@ -25,6 +25,8 @@ Note that this application is not meant to be run on web platform.
 
 If you want to use FVM to manage your Flutter versions effectively, please consult the [FVM (Flutter Version Management) guide](https://fvm.app/documentation/getting-started/installation) for comprehensive instructions on installing Flutter on your specific operating system.
 
+This project is currently using FVM 3.x.
+
 **Pro Tip:** Remember to prepend the 'flutter' prefix when using FVM commands, like this: `fvm flutter [command]`.
 
 ## Lila Server