bug#36496: [PATCH] Describe the rx notation in the lisp manual

[Drew Adams]

> The rx notation is useful and complex enough to merit inclusion in the
> manual.
>
> Right now, it's mainly described in the `rx' doc string, which is fairly
> well-written but quite long and a bit unstructured. Describing it in the
> manual permits a different pace and style of exposition, the inclusion of
> examples and related information, structured into separate sections with
> cross-references.

Indeed.  Bonne initiative !
Thanks for working on this.

Like `cl-loop' and Unix or GNU/Linux `find',
`rx' is practically a language unto itself.
But fortunately (unlike `cl-loop') it is
quite Lispy.