3205a92ad8 was a major commit which removed `PoolVector`, and replaced
most references to `PoolVector` with `Vector` instead. In most cases,
this was appropriate, given that `PoolVector` was being replaced with
`Vector`, as an effective generalist in 64-bit address space layouts.
However, vector.h itself was left with an artifact advising the reader
to use `Vector` instead of `Vector` for large arrays. While this led
to a fascinating deep dive, and hopefully improved some of the
documentation along the way, it's probably best to clean this up for
the next person.
66b7d5f1b5