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".
diff --git a/Doc/reference/introduction.rst b/Doc/reference/introduction.rst
index 62480bd..72e874e 100644
--- a/Doc/reference/introduction.rst
+++ b/Doc/reference/introduction.rst
@@ -93,7 +93,7 @@
The descriptions of lexical analysis and syntax use a modified BNF grammar
notation. This uses the following style of definition:
-.. productionlist::
+.. productionlist:: notation
name: `lc_letter` (`lc_letter` | "_")*
lc_letter: "a"..."z"