add new maintainers

[micahstubbs]

let's add some new maintainers and bring this repo back to life: I'll nominate

@tomshanley | https://github.com/tomshanley | https://blockbuilder.org/search?user=tomshanley&text=Sankey
@emeeks | https://github.com/emeeks | https://blockbuilder.org/search?user=emeeks&text=Sankey

as good candidates for new maintainers for their prolific work with and deep expertise of Sankey layouts.

[micahstubbs]

as others have noted, things around here have been kind of quiet recently. #64 let's change that 😄

[mbostock]

I’m still maintaining this repo and I welcome contributions, but I can’t make any guarantees as to how much time I have to dedicate to this repo (because of all the other ongoing work). If you’re dissatisfied with my level of engagement in this repo, please fork it and establish new maintainers. Thank you!

[micahstubbs]

understand, thanks for the reply 😄