bug#43942: message-insert-signature vs. always at the bottom

["積丹尼 Dan Jacobson" <jidanni@jidanni.org>]

       C-c C-w runs the command message-insert-signature (found in
       message-mode-map), which is an interactive compiled Lisp function in
       ‘message.el’.

       It is bound to C-c C-w, <menu-bar> <Message> <Insert Signature>.

       (message-insert-signature &optional FORCE)

Mention what's that FORCE is all about. User cannot tell from this page.

       Insert a signature.  See documentation for variable ‘message-signature’.

OK but there really should be a way of allowing the user to plant the
signature anywhere in the page, not always just at the end.

E.g., C-u C-c C-w could tell emacs "Assume point is the end of the
buffer, and do the same actions you would do there, here."

Currently one has to move the signature manually from where C-c C-w
planted it at the bottom of the buffer.

Sure, usually it is fine at the bottom of the buffer, but sometimes we
want to place it elsewhere.

emacs-version "26.3"