[Ada] Document pragma Ada_2022

[Pierre-Marie de Rodat via Gcc-patches]

Pragma Ada_2022 is similar to existing pragma Ada_2012 and similarly
deserves to be documented.

Tested on x86_64-pc-linux-gnu, committed on trunk

gcc/ada/

        * doc/gnat_rm/implementation_defined_pragmas.rst (Pragma
        Ada_2022): Copy description from pragma Ada 2012 and adapt.
        * doc/gnat_ugn/the_gnat_compilation_model.rst (Configuration
        Pragmas): List pragma Ada 2022.
        * gnat_rm.texi, gnat_ugn.texi: Regenerate.

patch.diff.gz
Description: application/gzip