May goals update

[tomassedovic]

Slightly less late than the April one ;-).

Rendered

[tomassedovic]

I've noticed there were several goals that mentiened "help needed", but not in the format our import tooling expected. So I've pulled them up to the help section manually.

I'm assuming that's what we want, but if not, it's in a separate commit that can be dropped easily.

[ehuss]

r? @rust-lang/goals

[tomassedovic]

Note: we'll need to update the publication date (in the path key) before we merge this.