The documentation of extraction became outdated when the big.ml wrapper
got modified by 094e4649c29e2426daca0476c140439de901dafe.

Signed primitive integers defined on top of the existing unsigned ones
with two's complement.

The module Sint63 includes the theory of signed primitive integers that
differs from the unsigned case.

Additions to the kernel:
  les (signed <=), lts (signed <), compares (signed compare),
  divs (signed division), rems (signed remainder),
  asr (arithmetic shift right)
(The s suffix is not used when importing the Sint63 module.)

The printing and parsing of primitive ints was updated and the
int63_syntax_plugin was removed (we use Number Notation instead).

A primitive int is parsed / printed as unsigned or signed depending on
the scope. In the default (Set Printing All) case, it is printed in
hexadecimal.

Persistent arrays expose a functional interface but are implemented
using an imperative data structure. The OCaml implementation is based on
Jean-Christophe Filliâtre's.

Co-authored-by: Benjamin Grégoire <Benjamin.Gregoire@inria.fr>
Co-authored-by: Gaëtan Gilbert <gaetan.gilbert@skyskimmer.net>

Reviewed-by: pi8027
Reviewed-by: zeldovich

Ack-by: Zimmi48
Reviewed-by: ppedrot

Also `Export ExtrHaskellBasic` in `ExtrHaskellString`.

Fixes #12257
Fixes #12258

There was also a non truly recursive in the doc.

Add headers to a few files which were missing them.