bpo-41762: Fix usage of productionlist markup in the doc (GH-22281)


Use an unique identifier for the different grammars documented using
the Sphinx productionlist markup.

productionlist markups of the same grammar, like "expressions" or
"compound statements", use the same identifier "python-grammar".
(cherry picked from commit 8af239eacfcf52e4e0e2b0223e7cea4672309483)

Co-authored-by: Victor Stinner <vstinner@python.org>
8 files changed