RE: Backslash-escaped brackets in string literals

[Drew Adams <drew.adams@oracle.com>]

> I think the manual should be amended at this point, and that
> we needn't require new doc strings to escape brackets in the leftmost
  ^^^^^^^^^^^^^^^^^^
> column.  Would this patch be acceptable for emacs-27?

"We need not" doesn't mean that no users of Elisp
need to use such escaping.

This messaging/doc is for everyone, not just the
developers who provide the code that GNU Emacs
distributes as part of Emacs.  And no user has ever
been "required" to use such escaping.  Let's keep
the target audience in mind: general Elisp users.

I think it's misleading and narrow to say "there
is no longer any need" for such escaping.

There can be such a need, if you're writing code
intended for more than just Emacs 27 and later.
3rd-party code is sometimes intended for multiple
releases.

In fact, it's probable that only a tiny minority
of Emacs users use the latest release, and only
the latest release.

It would be better to point out clearly that:

1. It never _hurts_ to provide such escaping.
2. Such escaping is appropriate for backward
   compatibility.  It presents no advantage for
   Emacs 27+, but it's helpful for older releases.