* lisp/emulation/cua-rect.el (cua--rectangle) (cua--last-rectangle, cua--restored-rectangle) (cua--rectangle-overlays, cua--rectangle-operation) (cua--tabify-start, cua--tabify-start, cua--insert-rectangle): Add docstrings, in several cases by converting existing comments. (Bug#30085) (cua--last-killed-rectangle): Update comment.