Review numpy 2.0 migration guide

[jtniehof]

We're finding 2.0 issues in CI and fixing them, and I think those are pretty well handled. Apparently binary wheels aren't compatible with 2.0 (although I haven't verified this) so we should be thinking of a new release soon-ish, since #749 is coming along.

As part of that, someone (happy to be me) should review the 2.0 migration guide and see if there's anything else we should be checking.