cleanup(docs): Edited API docs

modules/angular2/src/change_detection/pipes/pipe.js

@@ -1,10 +1,37 @@
+/**
+ * Indicates that the result of a [Pipe] transformation has not changed since the last time the pipe was called.
+ *
+ * Suppose we have a pipe that computes changes in an array by performing a simple diff operation. If
+ * we call this pipe with the same array twice, it will return `NO_CHANGE` the second time.
+ *
+ * @exportedAs angular2/pipes
+ */
+
 export var NO_CHANGE = new Object();
 
 /**
- * @exportedAs angular2/angular2
+ * An interface for extending the list of pipes known to Angular.
+ *
+ * If you are writing a custom [Pipe], you must extend this interface.
+ *
+ * #Example
+ *
+ * ```
+ * class DoublePipe extends Pipe {
+ *  supports(obj) {
+ *    return true;
+ *  }
+ *
+ *  transform(value) {
+ *    return `${value}${value}`;
+ *  }
+ * }
+ * ```
+ *
+ * @exportedAs angular2/pipes
  */
 export class Pipe {
   supports(obj):boolean {return false;}
   onDestroy() {}
   transform(value:any):any {return null;}
-}
+}