updated docs

CHANGELOG.md

+v0.1.10:
+  date: 2015-05-21
+  changes:
+    - missing attributes bug-fix
 v0.1.9:
   date: 2015-05-14
   changes:

CONTRIBUTING.md

 Contribution to the project is more than welcome! Please stick to the following rules:
 
 * all PRs must be shipped under the `develop` branch
-* releasing new version should include a new entry in [CHANGELOG.md](CHANGELOG.md) file
+* releasing new version should:
+  * include a new entry in [CHANGELOG.md](CHANGELOG.md) file
+  * be followed by rebuilding and re-releasing new online demo, see [gh-pages branch](https://github.com/pateketrueke/json-schema-faker/tree/gh-pages).