~littel-ponnys no longer maintains Eyre, so I will take over.
/lib/test goes without a dedicated maintainer for now.
Additionally, #4463 and follow-up work sees me taking charge of the terminal
stack, so I will take over formal ownership of that going forward.
The subtree in pkg/arvo apparently still has a README in it, which had
gotten only slightly out of sync with the overall project README. This
commit updates its 'contributing' section to point at the appropriate
contributing document.