Update command to make gctools global

README.md

@@ -7,7 +7,7 @@ Command line utilities for working with Ghost content.
 
 1. `git clone` this repo & `cd` into it as usual
 2. Run `yarn` to install top-level dependencies.
-3. To make `gctools` accessible globally, run `yarn global add`
+3. To make `gctools` accessible globally, run `npm link`
     - You need to run this after making changes to the codebase to update the global version
     - If developing the code, `yarn dev ...` is a more suitable command