docs: update Ti.Android.R and Ti.App.Android.R docs

apidoc/Titanium/Android/Android.yml

@@ -2148,7 +2148,7 @@ properties:
 
   - name: R
     summary: Accessor for Android system resources.
-    type: Titanium.Android.R
+    type: RProxy
     permission: read-only
     accessors: false
 

apidoc/Titanium/App/Android/Android.yml

@@ -11,7 +11,26 @@ platforms: [android]
 properties:
   - name: R
     summary: The `R` namespace for application resources.
-    type: Titanium.App.Android.R
+    description: |
+        The properties and sub-properties of this object relate directly to the native application
+        resources `R` class, and thus have the same syntax. For more information, refer to the
+        official documentation on the Android Developer website about
+        [accessing application resources](https://developer.android.com/guide/topics/resources/accessing-resources.html).
+
+        For example, if the file
+        `platform/android/res/drawable/icon.png` exists in the project, it can be accessed using its
+        integer id, as follows.
+
+            var resid = Titanium.App.Android.R.drawable.icon;
+
+        To access system-wide resources, rather than application resources, use <Titanium.Android.R>
+        instead.
+
+        Starting in Titanium SDK 7.3.0, this API exposes all Android related R classes
+        for the usage in Hyperloop. For example, it can be used to access `menu` resources
+        as part of native user interfaces, e.g. `BottomNavigationView` or `RecyclerView`.
+        See an example in the [Hyperloop Sample App](https://github.com/appcelerator/hyperloop-examples) for details!
+    type: RProxy
     permission: read-only
 
   - name: appVersionCode

apidoc/Titanium/Android/R.yml → apidoc/common/RProxy.yml

@@ -1,16 +1,27 @@
 ---
-name: Titanium.Android.R
-summary: The Titanium binding of the Android system-wide resources class.
+name: RProxy
+summary: |
+  The Titanium binding of the native Android `R` class, giving access to Android system-wide
+  resources or application resources.
 description: |
+    To access system-wide resources your application's resources, use <Titanium.Android.R>.
     To access your application's resources, use <Titanium.App.Android.R>.
 
-    These properties and sub-properties correspond directly to the properties of the the `android.R` 
-    class, and should have the same syntax. For example, to retrieve the "OK" string in Android:
-
+    These properties and sub-properties correspond directly to the properties of the the `android.R`
+    class, and should have the same syntax.
+    To retrieve the "OK" string from system resources in Android:
+
         Ti.Android.currentActivity.getString(Ti.Android.R.string.ok);
 
+    If the file  `platform/android/res/drawable/icon.png` exists in the project, it can be accessed
+    using its integer id, as follows:
+
+        var resid = Titanium.App.Android.R.drawable.icon;
+
     See also: [android.R](https://developer.android.com/reference/android/R.html) in the
     Android Developer Reference.
+    For more information, refer to the official documentation on the Android Developer website about
+    [accessing application resources](https://developer.android.com/guide/topics/resources/accessing-resources.html).
 
     Starting in Titanium SDK 7.3.0, this API exposes all Android related R classes
     for the usage in Hyperloop. For example, it can be used to access `menu` resources