Funding section in README

[ml-evs]

We may need to add a "funding" section to the README, but it's quite complicated (the funding section to the JOSS is already massive) -- I may have to do this as part of current PSDI-funded work though.

In terms of "major" funders, I would suggest:

• EPSRC, NOMAD, SPW Wallonie (for my contributions 2018-2024)
• PSDI / datalab.industries (for my ongoing work)
• Marketplace, NCCR & SINTEF(?) (for @CasperWA)
• CECAM (for @JPBergsma's work)

with an emphasis on the ongoing funding for maintenance @CasperWA and me, then add a note about other contributors being funded in other ways? Any thoughts @CasperWA?