docs(benchpress): add readme with instructions on using benchpress

Author: jeffbcross

benchmarks/README.md

@@ -0,0 +1,6 @@
+Instructions for using benchpress (how to create benchmarks, how to run, how to configure) can be
+found at: https://github.com/angular/benchpress/blob/master/README.md.
+
+In this project, there is a configured grunt task for building the benchmarks, and placing them in
+"/build/benchmarks/".
+The existing `grunt webserver` task can be used to serve the built benchmarks at `localhost:8000/build/benchmarks/<benchmark-name>`