Add guidelines on the use of example URLs in the Contributor Guide

[Darren Chan]

Based on a discussion with Brian Rosmaita:

1. For consistency, add guidelines to the Contributor Guide on the use of
example URLs in openstack-manuals and project documentation. Example.org is reserved by IANA for example URLs, so perhaps use the convention "project_name", then "openstack", followed by "example.org". For example:

http://glance.openstack.example.org/

2. Update example URLs in openstack-manuals to follow the above convention.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/421392

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/421392
Committed: https://git.openstack.org/cgit/openstack/openstack-manuals/commit/?id=57da5de0ab538e90924e69801440a7b19a0b9f01
Submitter: Jenkins
Branch: master

commit 57da5de0ab538e90924e69801440a7b19a0b9f01
Author: Alexandra Settle <email address hidden>
Date: Tue Jan 17 17:18:00 2017 +0000

    Add guidelines on the use of example URLs

    Change-Id: If83e0225e540dd1b6c88134737b50213485dd720
    Partial-bug: 1611176

[Alexandra Settle (alexandra-settle)]

Hi Iswarya,

This bug was not entire fixed, as you can see above I implemented a partial-fix.

The second half of this proposal: "Update example URLs in openstack-manuals to follow the above convention." Still needs to be carried out.