coding style missing in CONTRIBUTING.md

[jangtsekiang]

The following is a dead link:

Follow the JavaScript coding style defined in docs

Which can be found here.
Boost/CONTRIBUTING.md

I couldn't locate the folder.

[Rokt33r]

I'll update it.

[Rokt33r]

I think we don't need it now because we've introduced prettier! So, I'll close this issue.