Add documentation how to build the demo

.gitignore

@@ -1,4 +1,5 @@
 .nyc_output
+demo
 lib
 node_modules
 *.log

README.md

@@ -132,6 +132,19 @@ Compile to ES5 from /src to /lib
 npm run compile
 ```
 
+Initialize demo project
+```
+$ git clone [email protected]:One-com/react-truncate demo
+$ cd demo
+demo $ git checkout gh-pages
+demo $ npm install
+```
+
+Build demo
+```
+demo $ npm run compile
+```
+
 [npm-url]: https://npmjs.org/package/react-truncate
 [downloads-image]: http://img.shields.io/npm/dm/react-truncate.svg
 [npm-image]: https://badge.fury.io/js/react-truncate.svg