—BEFORE—
false, 0: do not store any revisions (except the one autosave per post)
(int) > 0: store that many revisions (+1 autosave) per post. Old revisions are automatically deleted.
—AFTER—
false, 0: do not store any revisions (except the one autosave per post and per user)
(int) > 0: store that many revisions (+1 autosave per user) per post. Old excess revisions are automatically deleted when the post is updated again.