Added progress sugar documentation in README.md

README.md

@@ -367,6 +367,36 @@ foo()
 })
 ```
 
+### Progress Notification
+
+It's possible for some promises to report their progress, especially
+if it's a task that takes a long time, or iterates. Not all promises
+may implement progress notifications.
+
+```javascript
+foo()
+.then(function (value) {
+    // Success processing foo and getting a value
+}, function(err) {
+    // There was an error, and we get the reason for error
+}, function(progress) {
+    // We get notified of foo()'s progress as it's executed
+})
+```
+
+like `fail`, Q also provides a shorthand for progress callbacks 
+called `progress`. 
+
+```javascript
+foo()
+.then(function (value) {
+    // Success processing foo()
+}).fail(function(err) {
+    // There was an error
+}).progress(function(prog) {
+    // We get notified of foo'd progress
+})
+```
 
 ### The End