Improve stratos usage docs

We should review all of our usage docs. Here is an example of something we need to review...
From slack:

Alejandro Bonilla @ABonilla 01:19:16
Neil MacDougall in the docs, when registering a Kubernetes, the docs just say

Enter the URL of the API server for your Kubernetes environment

which is very unclear. Perhaps we should put an example, because it expects the port and everything, not just a URL...

Also, when connecting a Metrics, it says:

Select Metrics from the Endpoint Type dropdown
Enter a memorable name for your environment in the Name field

Check the Skip SSL validation for the endpoint checkbox if using self-signed certificates

Click Finish

but there is also a field for a URL...

Alejandro Bonilla @ABonilla 01:31:56
now I know its lb:4433 but its very vague

Alejandro Bonilla @ABonilla 02:31:38
Neil MacDougall can we allow the option to have a system_shared kubeconfig (of a custom serviceaccount created) to allow all users to view the kubernetes stuff?
Trying for the experience to be easier
I know the current way allows for an easier role/access restriction, but perhaps there is a way to share view-only info? 🤷

Start by locating the usage documentation for registering Kubernetes and Metrics endpoints. Review the required URL, port, and SSL fields against the current instructions, and clarify whether the system_shared kubeconfig request is in scope. Done means the relevant setup steps and examples accurately describe the fields users must provide.