alias #to_hash to #to_h

[rmoriz]

Can we please add #to_h as an alias for #to_hash for:
https://github.com/reset/buff-config/blob/master/lib/buff/config.rb#L27

#to_h is rather the Ruby-default for various objects, e.g.

irb(main):002:0> [].to_h
=> {}