add android docs

docs/android.mdx

@@ -0,0 +1,24 @@
+# Check your AndroidManifest.xml   
+
+Check if you have the following in your `AndroidManifest.xml` file.  
+
+```xml
+<meta-data
+    android:name="flutterEmbedding"
+    android:value="2" />
+```
+
+Ideally you should have this, if not follow the [upgrade guide](https://github.com/flutter/flutter/wiki/Upgrading-pre-1.12-Android-projects).  
+If for some reason you can't upgrade yet we still support the [older way of embedding](ANDROID_SETUP_V1.md):
+
+# How to Debug my background job
+
+Debugging a background task can be difficult, Android decides when is the best time to run.  
+There is no guaranteed way to enforce a run of a job even in debug mode.  
+
+However to facilitate debugging, the plugin provides an `isInDebugMode` flag when initializing the plugin: `Workmanager().initialize(callbackDispatcher, isInDebugMode: true)`  
+
+Once this flag is enabled you will receive a notification whenever a background task was triggered.  
+This way you can keep track whether that task ran successfully or not.  
+
+ <img src=".art/android_debug_notification.gif" height="650">