File store documentation outdated

[waghanza]

Hi,

I've find this awesome shards, but it seems that the documentation is outdated, at least https://github.com/crystal-community/kiwi#filestore.

I've used what described in this documentation, but have a crystal error

Syntax error in tools/src/benchmarker.cr:16: expecting token ':', not ')'

I've found in the spec (and it works)

Kiwi::FileStore.new(dir: "/tmp/kiwi_test")

Regards,