Add linting rule enforcing reservation of capitals for constructors?

[achingbrain]

Context: ipfs-inactive/js-ipfs-http-client#1124 (comment)

Opening this here for any further discussion so the issue doesn't get lost.

I don't know if this is a good idea or if this is a rule in eslint we can enable, only that it's outside of the scope of ipfs-inactive/js-ipfs-http-client#1124

[daviddias]

Also make sure to reflect it on the contributing guidelines https://github.com/ipfs/community/blob/master/CONTRIBUTING_JS.md