Remove heroku related files and doc clean.

Author: shinxi

Procfile

@@ -3,10 +3,10 @@
 Let's say your project name is Foo. 
 
 * cd to Foo.
-* `npm run prod`
+* `npm run build`
 The command will generate all static files into build folder.
 * `npm run start:prod`
 You can test the build by run `npm run start:prod`, the command will bring up a node server which servers all static files under build foler. 
 Visit [http://localhost:5000](http://localhost:5000). If it works well, you'll see the page runs up.
 * Deploy. 
-Put the files under build folder into your web server.
+Put the files under build folder into your web server.