PEP 751: fix a spelling mistake (#4260)

Author: brettcannon

peps/pep-0751.rst

@@ -1045,8 +1045,8 @@ decide it wasn't worth trying to do in this PEP upfront. Instead, a future PEP
 could propose a solution.
 
 
-Recordinng possible extras and dependency groups
-================================================
+Recording possible extras and dependency groups
+===============================================
 
 To expand the feature set of this PEP such that tools could use this PEP for
 their main lock file format, recording possible extras and dependency groups