Update Quickstart guide - missing the step to add library

[theSteveMitchell]

I've tried In XCode 15.4 and 16, the instructions in the Quickstart guide don't work.

Expected:

• after adding the package dependency, I can copy-paste the example code into SceneDelegate, and then run the app

Actual:

• in SceneDelegate, I see a compiler error on the "import Turbo" statement, with the message No such module "Turbo"
• When I try to build or run the app, the build fails with the same error.

Resolution:
#228

• We need to add the Turbo library to the target after installing the package.