add develop branch in contributing

Author: vinicius73

README.md

@@ -95,11 +95,11 @@ $ composer test
 ## Contributing
 
 1. Fork it!
-2. Create your feature branch: `git checkout -b my-new-feature`
+2. Create your feature branch from **develop**: `git checkout -b my-new-feature`
 3. Write your code. Comment your code.
 4. Commit your changes: `git commit -am 'Add some feature'`
 5. Push to the branch: `git push origin my-new-feature`
-6. Submit a pull request :D
+6. Submit a pull request to **develop** branch :D
 
 ## Credits