Promote Cockpit in APIM Organization section

[siongravitee]

From Documentations Slack, Dorian said:

Hi, in the APIm doc we are saying that “By default, the OSS version of APIM comes with a default organization and a default environment. For a multi-environment setup, you need APIM Enterprise Edition.” Maybe we can update that to introduce Cockpit and the opportunity to have 2 envs using it for free. https://docs.gravitee.io/apim/3.x/apim_adminguide_organizations_and_environments.html

[plsstephenson]

Is the part of the statement about APIM Enterprise Edition true? This may need further investigation, and a clearer explanation of Enterprise Edition, what it gives you and how to get it, as well as its relationship to Cockpit (if any - does Cockpit form part of the Enterprise License?)