SP example implemented bindings not referenced in config

[spaceone]

The example for a SP implemented the following SAML bindings:

• BINDING_HTTP_REDIRECT
• BINDING_HTTP_POST
• BINDING_HTTP_ARTIFACT
• BINDING_SOAP

but the configuration in example/sp-wsgi/sp_conf.py.example contains only BINDING_HTTP_POST for the ACS.
All binding should be added with a comment that it is not necessary to support more than one binding.

[peppelinux]

Hi Florian, if you want to do a PR on the documentation I'm sure that @c00kiemon5ter Will be happy to get It in time. He's working a lot on the documentation, I think that's a good Moment for this