Added the alertDialog for info button

Author: tanvidadu

app/src/main/java/fr/free/nrw/commons/achievements/AchievementsActivity.java

@@ -43,6 +43,7 @@
 
 import butterknife.BindView;
 import butterknife.ButterKnife;
+import butterknife.OnClick;
 import fr.free.nrw.commons.R;
 import fr.free.nrw.commons.Utils;
 import fr.free.nrw.commons.auth.SessionManager;
@@ -135,6 +136,21 @@ protected void onCreate(Bundle savedInstanceState) {
         initDrawer();
     }
 
+    /**
+     * to invoke the AlertDialog on clicking info button
+     */
+    @OnClick(R.id.achievement_info)
+    public void showInfoDialog(){
+        new AlertDialog.Builder(AchievementsActivity.this)
+                .setTitle(R.string.Achievements)
+                .setMessage(R.string.achievements_info_message)
+                .setCancelable(true)
+                .setNeutralButton(android.R.string.ok, (dialog, id) -> dialog.cancel())
+                .create()
+                .show();
+
+    }
+
     @Override
     public boolean onCreateOptionsMenu(Menu menu) {
         // Inflate the menu; this adds items to the action bar if it is present.

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

@@ -293,4 +293,5 @@
   <string name="image_reverts">Images Not Reverted</string>
   <string name="images_used_by_wiki">Images Used By Wiki</string>
   <string name="achievements_share_message">Proceed to Share the Screenshot of Achievements</string>
+  <string name="achievements_info_message">The Quality as well as the Quantity of images uploaded makes up the criterion for determining the levels. For Each level there are certain requirements in terms of number of images uploaded, revert rate and images used by Wiki that needs to be met.</string>
 </resources>