Add config_version.sh example

Prior to this commit we had a pre-commit exmaple but not a
config_version example. This commit adds an example github script that
changes your prompt to something like this:

```shell
Info: Applying configuration version '[Fix
string](http://github.com/acidprime/puppet/tree/9e04bcea97bc5903b0328af3892ef95650b8fde9)'
```