Update docs to clarify common workflow regarding npm link of forked repo

[justin-hackin]

I'm wondering if there's a simpler way to achieve some of the workflow advantages mentioned in #15

Normally, when I create a PR for a dependency, I use npm link to test out the fix.

I had a fixed library still linked and I wondered if creating a patch from my changes would "just work" but the changes were not in the patch.

I can create a git patch file from my fix commit but then in order to apply it inside the node_modules, I'd guess that I'd have to edit every path mentioned in it. What if this was done programatically with a flag --from-fork=../my-forked-repo?

[justin-hackin]

When I wrote this issue, I was confused because of how Webstorm displays patch files 😳 Now I realize when you create a patch from a linked repo, all of the non-dist files end up in the patch. This is really easy to fix. In my case, I just needed to do npx patch-package package-name --include=dist so that non-build files aren't included 🎉

Would someone take a PR for a Readme update for others who can't just edit the JS in node_modules?