Description of problem:

The only mention of host_registration_insights parameter is in upstream:
https://docs.theforeman.org/nightly/Managing_Hosts/index-katello.html#Customizing_the_Registration_Templates_managing-hosts

We should add a mention that the parameter type is boolean.

While we are there, we should also mention that the same parameter also prevents hosts from appearing in rh_cloud reports if the parameter is set to false. Another usage of the parameter is to prevent insights-client from uploading its reports in case the parameter is set to false.