Explain context of "group" when initializing a project

[asmacdo]

In the Go docs this is all they have:

# we'll use a domain of example.com
# so all API groups will be <group>.example.com 

Lets Add a link to API groups and maybe an example of what the author should set it to.

[camilamacedo86]

@asmacdo,

we'll use a domain of example.com
so all API groups will be .example.com

Following my suggestion. See that it is more a tool limitation and that we acctually could/should be able to work with APIs from another domain mainly when we are trying to do scaffold to create controllers that will reconcile external types and core types. Also, has no conceptual reason to say that a project could not own APIs under different domains.

How and where is the domain informed used?

Currently, the tool does not support work with multi-domains to create the APIs by default. For more info check the issue kubebuilder/issues/2394 raised to add this support Therefore, you will check below that when you use the subCommand create api you will not need to inform the domain anymore. You will only inform the group, the Kind and the Version to create the APIs(s) and/or Controllers with the purpose to reconcile them and then, all will be scaffolded using this domain which is stored in the PROJECT file.

Be aware that you can work with external and core types which would have another domain, but the tool is not fully helping out with. For further info see the issue kubebuilder/issues/1999.

c/c @jberkhahn @laxmikantbpandhare