Add some documentation.

Author: frontid

README.md

@@ -1 +1,20 @@
 # jQueryIsInViewport
+
+This plugin allows you to react when an element is in the viewport.
+You need throw confetti when the user scroll and see an element?, so this plugin is for you!
+
+## Usage
+```javascript
+$('.block').isInViewport(function (status) {
+  if (status === 'entered') {
+    $(this).addClass('throw-confetti')
+  }
+
+  if (status === 'leaved') {
+    $(this).removeClass('throw-confetti')
+  }
+})
+```
+
+## Options
+Status can be '**entered**' or '**leaved**'.