specs: fix a comment typo.

* lib/zemacs/specs/zlisp_move_spec.yaml (forward-line): Fix
comment to refer to forward-line correctly.

Signed-off-by: Gary V. Vaughan <gary@gnu.org>
specs: add a checklist, apply it to zlisp_move_spec.yaml.

* lib/zemacs/specs/README: New file.  A checklist of what needs
to be specified for each ZLisp built-in command.
* lib/zemacs/specs/zlisp_move_spec.yaml (beginning-of-line)
(end-of-line, backward-char, forward-char): Adjust specifications
to satisfy checklist.

Signed-off-by: Gary V. Vaughan <gary@gnu.org>