Update README.md

[DoctorDerek]

Hey, I just wanted to leave a note that the README assumes someone's on a *nix system, so the multi-line instructions should probably be written as three separate lines.

After all, most terminals accept multi-line inputs, right? 😀

I updated the README to make this change:

npm install husky@6 --save-dev
npx husky-init
npm exec -- github:typicode/husky-4-to-6 --remove-v4-config

[DoctorDerek]

Also #10 is still open and true (npm exec requires npm >v7) -- I actually updated npm to latest because it didn't make any sense to me that npm exec is a new command, but that's also in the README.

[DoctorDerek]

Finally, I should put out that this PR #18 does not actually provide a great user experience on Windows, but at least it's not such a terrible one.

I can understand why you'd be using \ && -- but that particular code is basically unusable on Windows (I have to meticulously look at each line to remove the \).

[DoctorDerek]

Or maybe npx --no-install husky-init would work.