Update README.md

Author: Ashok-Varma

README.md

@@ -1,5 +1,6 @@
 # BottomNavigation
 
+<img src="https://raw.githubusercontent.com/Ashok-Varma/BottomNavigation/master/complete.gif" width="300" height="550" />
 
 ## What is this component about?
 
@@ -42,7 +43,7 @@ or Ivy:
 ```
 ### Usage
 
-####Basic setup
+#### Basic setup
 
 in your activity xml :
 
@@ -66,6 +67,22 @@ bottomNavigationBar
                 .addItem(new BottomNavigationItem(R.drawable.ic_videogame_asset_white_24dp, "Games"))
                 .initialise();
 ```
+#### Add TabChangeListener
+
+```java
+        bottomNavigationBar.setTabSelectedListener(new BottomNavigationBar.OnTabSelectedListener(){
+            @Override
+            public void onTabSelected(int position) {
+            }
+            @Override
+            public void onTabUnselected(int position) {]
+            }
+            @Override
+            public void onTabReselected(int position) {
+            }
+        });
+```
+all methods are self explanatory
 
 #### BottomNavigationBar Cutomisations
 
@@ -74,7 +91,7 @@ bottomNavigationBar
 BACKGROUND_STYLE_STATIC | <img src="https://raw.githubusercontent.com/Ashok-Varma/BottomNavigation/master/classic_static.gif" width="320" height="50" /> | <img src="https://raw.githubusercontent.com/Ashok-Varma/BottomNavigation/master/shift_static.gif" width="320" height="50" />
 BACKGROUND_STYLE_RIPPLE | <img src="https://raw.githubusercontent.com/Ashok-Varma/BottomNavigation/master/classic_ripple.gif" width="320" height="50" /> | <img src="https://raw.githubusercontent.com/Ashok-Varma/BottomNavigation/master/shift_ripple.gif" width="320" height="50" />
 
-##### Modes
+##### 1) Modes
 library provides two modes MODE_CLASSIC and MODE_SHIFTING
 
 to set mode :
@@ -85,18 +102,18 @@ bottomNavigationBar
 ###### default behaviour
 MODE_DEFAULT: if number of tabs are less than or equal to three then MODE_CLASSIC will be used other cases MODE_SHIFTING will be used.
 
-##### Background Styles
+##### 2) Background Styles
 library provides two background styles BACKGROUND_STYLE_STATIC and BACKGROUND_STYLE_RIPPLE
 
-you can set background style:
+to set background style:
 ```java
 bottomNavigationBar
                 .setBackgroundStyle(BottomNavigationBar.BACKGROUND_STYLE_RIPPLE)
 ```
 ###### default behaviour
 BACKGROUND_STYLE_DEFAULT: if mode is MODE_CLASSIC then BACKGROUND_STYLE_STATIC will be used if mode is MODE_SHIFTING then BACKGROUND_STYLE_RIPPLE will be used.
 
-##### Colors
+##### 3) Colors
 user can play with three colors : background color, active color and in-active color
 
 in-active color : is the icon and text color of the in-active/un-selected tab