Add announcement for the Open-Energy-Modeling project

[odow]

I haven't heard back from our unnamed benefactor about mentioning them, but I'd like to softly announce this since we're starting work.

We can update the text with a description of the benefactor and announce properly on socials etc if I get the go ahead at a later date.

cc @jajhall cc @galabovaa cc @joaquimg

[odow]

I still haven't heard back from our benefactor, so I'm open to suggestions on whether we should just merge this as-is.

[jajhall]

Yes, merge it as is. I had a similar difficulty with Google/Tides, who were promising a big announcement that never happened

[odow]

Breakthrough got back to me:

We are low key. We typically won’t do announcements for individual projects. You are welcome to acknowledge our support - primarily to support the integrity of the work. Please limit the use of the breakthrough energy logo.

so I have now named them in the post.