Link to update repository is incorrect in release notes

[Eugene Nikanorov]

https://docs.mirantis.com/openstack/fuel/fuel-6.0/release-notes.html#updates-neutron-rn

The document describes update procedure and mentions the link fuel-repository.mirantis.com/mirror/fwm/6.0/updates/
where http://mirror.fuel-infra.org/fwm/6.0/updates/ is actual working link

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/6.0
Review: https://review.openstack.org/212408

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/212408
Committed: https://git.openstack.org/cgit/stackforge/fuel-docs/commit/?id=9adb8a2746bc9a2c3e94cb1c0c85fea1b6ef153a
Submitter: Jenkins
Branch: stable/6.0

commit 9adb8a2746bc9a2c3e94cb1c0c85fea1b6ef153a
Author: Olena Logvinova <email address hidden>
Date: Thu Aug 13 11:29:32 2015 +0300

    [RN] Change a non-working update link

    This patch replaces a non-working update link
    fuel-repository.mirantis.com/mirror/fwm/6.0/updates/
    with a working one.

    Change-Id: Ia73d07b9accf3a98b865ac28ab4a3f2f566c16ae
    Closes-Bug: #1484270