Adding ionic4 project to angular 7 workspace

I have angular7 and ionic4 apps in completely different folders. The services code is duplicated.
I want to take advantage of the angular workspace. I want to make one service library and use both in the ionic and angular 7 app.

I saw on the github

ng add @ionic/angular.

Is this correct? Please add this to the docs. It was quite bit of effort to search for this.

It’s already in the doc, chapter “Installing Ionic from a CDN”