Update ReadMe.md

Sub-GHz/Settings/ReadMe.md

@@ -1,5 +1,16 @@
 # Adding additional frequencies (TX/RX)
 
+Official firmware now uses a different method for region locks. Per Aleksandr Kutuzov (skotopes):
+```
+Mobile app uses Phone/SIM region with fallback to GeoIP.
+Desktop uses GeoIP and fallback to System.
+```
+This data is stored in the `.region_data` (hidden) file within internal storage and is set when connected to Desktop/Mobile per above.<br>
+If you're having issues with regional retrictions that do not match your region, you can use the `region_data_null` file here.<br>
+Simply download and rename it to `.region_data` then replace the one currently in your internal storage.
+
+NOTE: This _will_ be overwritten each time you sync to the mobile app or qFlipper! Only for testing/verification purposes.
+
 ## Note: You must be on the latest release!
 
 Some changes I made to the available frequency settings (including unlocking them all). The file is found here:
@@ -35,4 +46,4 @@ So, here it is. All donations of *any* size are humbly appreciated.<br>
 ![Flipper_Clap](https://user-images.githubusercontent.com/57457139/183561789-2e853ede-8ef7-41e8-a67c-716225177e5d.jpg) ![Flipper_OMG](https://user-images.githubusercontent.com/57457139/183561787-e21bdc1e-b316-4e67-b327-5129503d0313.jpg)
 
 Donations will be used for hardware (and maybe caffeine) to further testing!<br>
-![UberGuidoZ](https://cdn.discordapp.com/emojis/1000632669622767686.gif)
+![UberGuidoZ](https://cdn.discordapp.com/emojis/1000632669622767686.gif)