replace husky add in readme

[nemchik]

husky add is deprecated, use echo instead

I also included passing the --lockfile argument in the example as I believe it's the most desirable default behavior. The important thing to do there is adding the -- right before package-changed so that the --lockfile argument is passed to package-changed and not read by npx itself.

p.s. I accidentally created nemchik#5 months ago instead of creating it correctly here 😆