DOC updates [skip ci]

updated README.md
update CONTRIBUTING.md
add docs/getting_started_on_windows.md
[skip ci]
While following this I got this error
```bash
There are errors in the configuration of this machine. Please fix
the following errors and try again:

Vagrant:
* Unknown configuration section 'vbguest'.
```

The following fixes it, should this be added?
`vagrant plugin install vagrant-vbguest`