Merge "Correct parentActivity example in Activity Element docs."

<activity

    android:name="com.example.app.ChildActivity"

    android:label="@string/title_child_activity"

    android:parentActivityName="com.example.myfirstapp.MainActivity" >

    android:parentActivityName="com.example.app.MainActivity" >

    <!-- Parent activity meta-data to support API level 4+ -->

    <meta-data

        android:name="android.support.PARENT_ACTIVITY"