message: add explanation how to link build version
diff: @@ -109,6 +109,10 @@ To run tests in another project with the development build of Jest:
  ```sh
  cd /path/to/another/project
  +
  +# link development build to the other project
  +yarn link jest-cli
  +
  jest [options] # run jest-cli/bin/jest.js in the development build
  ```
  