Update README.md

Usage with Gulp.js

Author: Grawl

README.md

@@ -25,6 +25,25 @@ var output = postcss([
 ]).process(css);
 ```
 
+### Usage with Gulp.js
+
+```js
+gulp.task('cssstats', function(){
+    var cssstats = require('postcss-cssstats');
+    var postcss = require('gulp-postcss');
+    return gulp
+        .src('/path/to/file.css')
+        .pipe(
+        postcss([
+            cssstats(
+                function(stats) {
+                  console.log(stats);
+                })
+            ])
+        );
+});
+```
+
 ## License
 
 MIT