Updated Android (markdown)

Android.md

@@ -134,3 +134,25 @@ public class EbitenGLSurfaceView extends GLSurfaceView {
     }
 }
 ```
+
+Note that `Seq.setContext` must be called when the activity is created.
+
+```java
+// ...
+
+import go.Seq;
+
+public class MainActivity extends AppCompatActivity {
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_main);
+        Seq.setContext(getApplicationContext());
+    }
+
+    // ...
+
+}
+```
+```