Feature request: Add a generating feature of default cspell.json

[zacky1972]

Hi,

This is nice! I favor it!

I've just install this, and I was amazed and impressed with how effortlessly I was able to set up credo, dialyxir and ex_doc, though the only thing I found disappointing was that they didn't provide a default initial configuration file for cspell.json, which is required for setting up spellweaver.

So, I propose to add a generating feature of default cspell.json.