bpo-46831: Update __build_class__ comment (GH-31522)

Co-authored-by: Jelle Zijlstra <[email protected]>
(cherry picked from commit 81d968b)

Co-authored-by: Shantanu <[email protected]>

Author: miss-islington

Python/compile.c

@@ -2440,9 +2440,8 @@ compiler_class(struct compiler *c, stmt_ty s)
     /* ultimately generate code for:
          <name> = __build_class__(<func>, <name>, *<bases>, **<keywords>)
        where:
-         <func> is a function/closure created from the class body;
-            it has a single argument (__locals__) where the dict
-            (or MutableSequence) representing the locals is passed
+         <func> is a zero arg function/closure created from the class body.
+            It mutates its locals to build the class namespace.
          <name> is the class name
          <bases> is the positional arguments and *varargs argument
          <keywords> is the keyword arguments and **kwds argument