Issue #31: Updating the Docs with Parallel Bars example

This commit adds the documentation for the README.md, along with the
description of the result of running the example.

*	modified:   README.md
- Some refactoring
- Adding the example

*	new file:   example/multiple.go
- Adding the example provided during the discusion of issue 31
- Adding the correct import statement for "pb"
Merge pull request #32 from marcellodesales/multiple

Issue #31: Updating the Docs with Parallel Bars example