Add notes API examples (already supported)

[ludstuen90]

Description of the problem, including code/CLI snippet

Documentation does not include an example of how to use python-gitlab to view notes

Expected Behavior

The documentation should contain an API example of how to view notes. This would document functionality that already exists in this plugin:
notes_list = mr.notes.list()

Actual Behavior

This documentation does not exist.

[gpocentek]

Hi @ludstuen90

Thanks for reporting this issue. The documentation exists in the projects page: http://python-gitlab.readthedocs.io/en/master/gl_objects/projects.html?#notes

This is probably not the best place though, so I'll move it somewhere more visible.

[ludstuen90]

@gpocentek That's it! Thanks for pointing that out -- appreciate it!