Recursive create

[levithomason]

Thanks for this package, was about to make the same thing.

Currently --update-index recursively searches for index files to update. However, when creating indexes there is no recursive option. It looks like it was considered in #2 as a --deep option. I cannot find it in the source or docs though.

I'm looking for a single command to create and update index files recursively. This way I can create-index ./src --deep or more preferred create-index ./src/**/ and always count on all directories having an index.

Are you open to PRs for accepting globs or a --deep option on create-index ./src?