docs: update Ti.Android.R and Ti.App.Android.R docs (#11492)

Co-authored-by: Jan Vennemann <jan.vennemann@gmx.net>

apidoc/Titanium/Android/Android.yml

@@ -2148,6 +2148,8 @@ properties:
 
   - name: R
     summary: Accessor for Android system resources.
+    description: |
+        To access your application's resources, use <Titanium.App.Android.R>.
     type: Titanium.Android.R
     permission: read-only
     accessors: false

apidoc/Titanium/Android/R.yml

@@ -1,16 +1,30 @@
 ---
 name: Titanium.Android.R
-summary: The Titanium binding of the Android system-wide resources class.
+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);
 
-    See also: [android.R](https://developer.android.com/reference/android/R.html) in the
+    If the file  `platform/android/res/drawable/icon.png` exists in the
+    project, it can be accessed using its resource name, 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

apidoc/Titanium/App/Android/Android.yml

@@ -11,7 +11,22 @@ 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 resource name,
+        as follows.
+
+            var resid = Titanium.App.Android.R.drawable.icon;
+
+        To access system-wide resources, rather than application resources, use
+        <Titanium.Android.R> instead.
+    type: Titanium.Android.R
     permission: read-only
 
   - name: appVersionCode