[DOC] Inform operators about quota requirements (security group rules) for some plugins

[Luigi Toscano]

When auto_security_group is used, the amount of created security group rules for some plugins (at least HDP 2.0.6) is bigger than the default values configured in neutron.conf (100 for security group rules).

While this is is usually tuned when a tenant/project is created, an out-of-the-box tenant is not able to create a cluster.

Also, the Sahara CI greatly increases the quota when tests are executed:
http://git.openstack.org/cgit/openstack/sahara-ci-config/tree/config/devstack/local.sh#n63

The documentation should state that the default limit should be raised. I didn't submit a patch for review because I'm not sure:
- where this should go ("Hortonworks Data Platform Plugin" page or a more general place.
- whether the note should only suggest to increase the value or if it should specify a (reasonable) value that can cover many cases, or a formula to find out how many rules are needed based on the size of the cluster.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/337245

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/337245
Committed: https://git.openstack.org/cgit/openstack/sahara/commit/?id=e1b9ff851e12599b216967248ea5a838ee12ad75
Submitter: Jenkins
Branch: master

commit e1b9ff851e12599b216967248ea5a838ee12ad75
Author: Michael Ionkin <email address hidden>
Date: Mon Jul 4 17:15:03 2016 +0300

    [DOC] Inform operators about limited quotas

    Added information about limited default security group rules
    quotas and how operator can fix it.

    Change-Id: Id06641cd9e433119c9740eaf41e6ea3e44a22cdf
    closes-bug: 1543157

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/sahara 5.0.0.0b3 development milestone.