Added details activity label

Author: jakubdolejs

app/src/main/AndroidManifest.xml

@@ -14,7 +14,9 @@
         android:roundIcon="@mipmap/ic_launcher_round"
         android:supportsRtl="true"
         android:theme="@style/Theme.AppCompat.Light.DarkActionBar">
-        <activity android:name=".DocumentDetailsActivity"></activity>
+        <activity
+            android:name=".DocumentDetailsActivity"
+            android:label="@string/details"></activity>
         <activity
             android:name=".AboutActivity"
             android:label="@string/about" />