Update example shell integration to show shimming

[iamogbz]

Made a tool, nvshim, for shimming node binaries using nvm. Useful as an option for people that do not want to add auto loading script to their shell.

Unsure of the community rules about self promotion, just thought to share since it's been working for myself and a couple others.

[sladyn98]

I guess this would need to be on hold till the caveats are resolved and merged in master. Would be good to have an waiting-on-author label here : )

[iamogbz]

@sladyn98 @ljharb updated the documentation here and on nvshim caveats to indicate specifically what gets shimmed.