activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/drawer_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:openDrawer="start">

    <include
        layout="@layout/app_bar_main"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

    <android.support.design.widget.NavigationView
        android:id="@+id/nav_view"
        style="@style/NavigationView"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        android:fitsSystemWindows="true"
        app:headerLayout="@layout/nav_header_main"
        app:itemIconTint="@color/nav_item_selector"
        app:itemTextColor="#fff"
        app:menu="@menu/activity_main_drawer">

        <RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent">

            <TextView
                android:id="@+id/version"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_above="@+id/logout_btn"
                android:layout_gravity="bottom"
                android:background="#222"
                android:gravity="center"
                android:padding="20dp"
                android:textColor="#ccc"
                android:textSize="12sp"
                tools:text="1.0.0 staging" />

            <Button
                android:id="@+id/logout_btn"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_alignParentBottom="true"
                android:background="@color/colorPrimaryDark"
                android:text="@string/logout"
                android:textColor="@android:color/white" />
        </RelativeLayout>

    </android.support.design.widget.NavigationView>

</android.support.v4.widget.DrawerLayout>