gh-110886 Doc: add a link to BNF Wikipedia article (#110887)

partev · hugovk · web-flow · commit 42a5d21d465f · 2023-10-15T10:52:13.000-06:00
Co-authored-by: Hugo van Kemenade &lt;hugovk@users.noreply.github.com&gt;
diff --git a/Doc/reference/introduction.rst b/Doc/reference/introduction.rst
@@ -90,7 +90,8 @@ Notation
 
 .. index:: BNF, grammar, syntax, notation
 
-The descriptions of lexical analysis and syntax use a modified BNF grammar
+The descriptions of lexical analysis and syntax use a modified
+`Backus–Naur form (BNF) <https://en.wikipedia.org/wiki/Backus%E2%80%93Naur_form>`_ grammar
 notation.  This uses the following style of definition:
 
 .. productionlist:: notation
