[Bug c/70967] doc: Please document rotate idiom

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70967

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2022-01-10

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed, though I don't know where in the documenation would be a good place
to put it.