Good news - we actually released Ionic CLI 6.0.0 under the npm tag @ionic/cli within the last week. This has been a long time coming and it took some convincing internally to get a more descriptive package name, but I think this will help in the future! We tweeted about this earlier: https://twitter.com/Ionicframework/status/1223268498362851330?s=20
The documentation on the site has been updated to reflect this: How to Install The Ionic Framework CLI to Build Mobile Apps
The older package will live on since there are so many tutorials out there that use the ionic package, but this is a step in the right direction.
As for how to respond to any package confusion, I wrote up a response awhile back that may be helpful to link to:
Usually when we see incorrect packages being referenced we’ll recommend running ionic info from within the project as that gives the best overview of the different packages & their versions. Hopefully that helps. 