Fix misleading comment at the top of procfile.rb that indicates that hyphens "-" are not allowed in process names.

[benwilber]

Several of the ports listed in the README have incorrectly not allowed hyphens to be present in process names. I believe it's because they took inspiration from this misleading comment at the top of the procfile.rb file.

Haskell

Go

Java

The actual regex used does permit hyphens in process names.

[ddollar]

Thank you!