rad deploy parameters should be documented in a more visible place

[rynowak]

We should make the guidance about how to use parameters and when to use parameters more visible. Ideally this could be a quickstart.

Right now the only way to find out about parameter support is through the CLI help, or this page https://edge.radapp.dev/reference/cli/rad_deploy/

Thanks @sylvainsf for the find

AB#7109

[sylvainsf]

Additionally there aren't any examples of actually using the parameters in your bicep, and the linked documentation to parameter files doesn't have info on it either.