Fixed incorrect string for color filter (#493)

app/src/main/res/menu/reader.xml

@@ -4,16 +4,15 @@
 
     <item
         android:id="@+id/action_custom_filter"
-        android:title="@string/label_settings"
         android:icon="@drawable/ic_brightness_4_white_24dp"
-        app:showAsAction="ifRoom"
-        />
+        android:title="@string/custom_filter"
+        app:showAsAction="ifRoom" />
 
     <item
         android:id="@+id/action_settings"
-        android:title="@string/label_settings"
         android:icon="@drawable/ic_settings_white_24dp"
+        android:title="@string/label_settings"
         app:showAsAction="ifRoom"
         />
 
-</menu>
+</menu>

app/src/main/res/values/strings.xml

@@ -275,6 +275,7 @@
 
 
     <!-- Reader activity -->
+    <string name="custom_filter">Custom filter</string>
     <string name="downloading">Downloading…</string>
     <string name="download_progress">Downloaded %1$d%%</string>
     <string name="chapter_progress">Page: %1$d</string>