[docs] Address in dev docs how to contribute to existing puppet module in fuel-library

[Bogdan Dobrelya]

The dev-docs [0] does not contain a description of how to contribute to existing modules. Since we changed reviewing policy after merging upstream manifests in fuel-library, we have to explain new contributing/reviewing rules publicly.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/129191

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/129191
Committed: https://git.openstack.org/cgit/stackforge/fuel-web/commit/?id=ae3c2885a41a7df5c0efd21c9d6dbe1373e5b52f
Submitter: Jenkins
Branch: master

commit ae3c2885a41a7df5c0efd21c9d6dbe1373e5b52f
Author: Bogdan Dobrelya <email address hidden>
Date: Fri Oct 17 11:45:54 2014 +0200

    Address how to contribute to existing modules

    W/o this patch, it is unclear how to contribute
    to existing fuel library modules. In order to fix this,
    fuel dev docs should be updated as appropriate.

    Closes-bug: #1382432

    Change-Id: I3d152c9b09297f3ae01e54f364723ef904f9f7c5
    Signed-off-by: Bogdan Dobrelya <email address hidden>