add example for flatmap and filter

readme.markdown

@@ -99,10 +99,30 @@ Same as `map`, but the callback is called synchronously. Based on `es.through`
 
 Map elements nested.
 
+``` js
+var es = require('event-stream')
+
+es.flatmapSync(function (data) {
+  //transform data
+  // ...
+  return data
+})
+
+```
+
 ## filterSync (syncFunction)
 
 Filter elements.
 
+``` js
+var es = require('event-stream')
+
+es.filterSync(function (data) {
+  return data > 0
+})
+
+```
+
 ## split (matcher)
 
 Break up a stream and reassemble it so that each line is a chunk. matcher may be a `String`, or a `RegExp`