[docs] Document procedure on keeping master node up-to-date

[Vladimir Kuklin]

Whenever a user installs (or upgrades to) 6.1 GA his installation may contain not all the latest bugfixes and updates as there could be new patches delivered as part of update bundle which is released on regular basis by MOS and Fuel teams.
This means that if user wants to install latest environments wit

This also means that if user wants to install new environments or do manipulations with existing ones (starting with 6.1 versions) he needs to keep master node state synchronized with nodes of the environments, e.g environment being manipulated should have the same set of repos configured as master node has and master node should have installed latest packages from these repos by applying following commands:

`List of commands to come`

Also, user should know that update repositories that are configured should be
accessible from all nodes in order for updates to be consumed.

[Irina Povolotskaya (ipovolotskaya)]

Guys, I've confirmed it for 6.1 as well. Please, assign this bug to any of your teammates.

[Igor Shishkin (teran)]

Moving to 6.1-updates since 6.1 is already released.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/224839

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/224839
Committed: https://git.openstack.org/cgit/stackforge/fuel-docs/commit/?id=4ac7c3cf8ceb6860155d4b27667f08719780970c
Submitter: Jenkins
Branch: master

commit 4ac7c3cf8ceb6860155d4b27667f08719780970c
Author: Svetlana Karslioglu <email address hidden>
Date: Thu Sep 17 10:21:05 2015 -0700

    Add a procedure on keeping master node updated

    Added a section that describes how to keep
    the Fuel Master node up-to-date

    Change-Id: Idaebab0bc6fad70b0826955a35e278106d7ff7e4
    Closes-Bug: #1466430

[Nastya Urlapova (aurlapova)]

https://docs.mirantis.com/fuel/fuel-master/operations.html#verifying-the-installed-packages-on-the-fuel-master-node