Revise the ImageButton class description to include information

/**

 * <p>

 * An image button displays an image that can be pressed, or clicked, by the

 * user.

 * </p>

 * Displays a button with an image (instead of text) that can be pressed 

 * or clicked by the user. By default, an ImageButton looks like a regular 

 * {@link android.widget.Button}, with the standard button background

 * that changes color during different button states. The image on the surface

 * of the button is defined either by the {@code android:src} attribute in the

 * {@code <ImageButton>} XML element or by the 

 * {@link #setImageResource(int)} method.</p>

 * 

 * <p>To remove the standard button background image, define your own 

 * background image or set the background color to be transparent.</p>

 * <p>To indicate the different button states (focused, selected, etc.), you can

 * define a different image for each state. E.g., a blue image by default, an

 * orange one for when focused, and a yellow one for when pressed. An easy way to

 * do this is with an XML drawable "selector." For example:</p>

 * <pre>

 * <?xml version="1.0" encoding="utf-8"?>

 * <selector xmlns:android="http://schemas.android.com/apk/res/android">

 *     <item android:drawable="@drawable/button_normal" /> <!-- default -->

 *     <item android:state_pressed="true"

 *           android:drawable="@drawable/button_pressed" /> <!-- pressed -->

 *     <item android:state_focused="true"

 *           android:drawable="@drawable/button_focused" /> <!-- focused -->

 * &lt;/selector&gt;</pre>

 *

 * <p>Save the XML file in your project {@code res/drawable/} folder and then 

 * reference it as a drawable for the source of your ImageButton (in the 

 * {@code android:src} attribute). Android will automatically change the image 

 * based on the state of the button and the corresponding images

 * defined in the XML.</p>

 *

 * <p><strong>XML attributes</strong></p>

 * <p>