actually add ripple effect on the reader toolbar

I was pretty sure I committed this in c26c38ca3 but here we are

It was just square ripple at first, but adding a new drawable with padding

app/src/main/res/drawable/reader_toolbar_ripple.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
+    <item android:end="96dp" android:start="48dp" android:drawable="@drawable/square_ripple"/>
+</layer-list>

app/src/main/res/layout/reader_activity.xml

@@ -56,7 +56,7 @@
                 android:id="@+id/toolbar"
                 android:layout_width="match_parent"
                 android:layout_height="?attr/actionBarSize"
-                android:background="@android:color/transparent" />
+                android:background="@drawable/reader_toolbar_ripple" />
 
         </FrameLayout>
     </FrameLayout>