Add simple configuration guides for all supported OpenStack services

[janhorstmann]

Part of osism/issues#938

[janhorstmann]

I have taken the list of supported services from the release respository version 7.0.0

Do you want to keep the links currently used in the nova docs or want it to be more uniform?

The skyline-apiserver project seems not to have an admin guide, so I have not added a link

[berendt]

Use a single skyline file and add console & api server there.

Add additional neutron services (dynamic routing, vpnaas) to the neutron file and not in separate files.

[berendt]

Always add a link (if it exists) to the configuration reference (like https://docs.openstack.org/nova/latest/configuration/config.html) as well.

[berendt]

For some services the configuration guide is the same like the configuration reference. In this case only add a single link and name it configuration reference.

The configuration reference is the page of all usable configuration parameters.

The configuration guide explains how to configure specific features.

[berendt]

As commented before.

[janhorstmann]

For some services the configuration guide is the same like the configuration reference. In this case only add a single link and name it configuration reference.

The configuration reference is the page of all usable configuration parameters.

The configuration guide explains how to configure specific features.

Some services have sites titled "configuration guide", which only link to the configuration reference of one or more applications. Ich have included those as "configuration reference" now, because they do not provide any further guidance, but the mismatch might be irritating for some.