Add snippet for react custom hook

[41y08h]

Hey reader,
Glad to see you're reading this, I was just creating some custom hooks in my projects and noticed that this very awesome VSCode extension doesn't have this snippet. I think creating a custom hook is a really cool feature of react.js and just modifying rfc snippet is a lot of work in the long run so I thought it would be nice to have this snippet also, looking forward to seeing you merge this. Thanks : )

Tested in VSCode custom snippets.

[41y08h]

Hey Damian, I'm glad you approved this PR but this is not working as intended, this is not the snippet included in this PR but the snippet created using rch is very similar to the snippet created using rafc.

Please check using rfc, and look at the snippet created, and the PR approved, they are not the same.

Thanks for viewing and merging this PR.

[ice-chillios]

@41y08h I've made changes to your snippet but inspired by it :)