Add the on-line URL of document on GitHub Pages.

Author: Minggang Wang

README.md

@@ -121,7 +121,7 @@ There are also several useful examples under the `example` folder, which will sh
 
 ## API Specification
 
-The API spec is generated by `jsdoc`, you can manually run `npm run docs` to create them by yourself, or just use the existing documents under `docs` folder.
+The API spec is generated by `jsdoc`, you can manually run `npm run docs` to create them by yourself, or just use the existing documents under `docs` folder. To visit the on-line version, please navigate to http://robotwebtools.org/rclnodejs/docs/index.html in your browser.
 
 ## Contributing