Update README.md

Added the required permissions in the geolocation plugin documentation so that the code example can run.

Author: jbousquie

plugins/geolocation/README.md

@@ -91,7 +91,16 @@ fn main() {
         .expect("error while running tauri application");
 }
 ```
-
+Then, for instance, grant the plugin the permission to check or request permissions from the user and to read the device position in the file `src-tauri/capabilities/default.json`
+```
+  "permissions": [
+    "core:default",
+    "geolocation:allow-check-permissions",
+    "geolocation:allow-request-permissions",
+    "geolocation:allow-get-current-position",
+    "geolocation:allow-watch-position",
+  ]
+```
 Afterwards all the plugin's APIs are available through the JavaScript guest bindings:
 
 ```javascript