Merged
requested to merge github/fork/nickmccurdy/explain-how-to-uninstall-create-react-app-globally into master
I've noticed a few times that users will read the error about having to uninstall create-react-app, not know how to do that, and then get stuck and have to ask for help. This adds uninstallation advice (similar to what's in the readme) at the bottom of the error messages, and also includes yarn.