pythongh-112165: Fix typo in __main__.py (pythonGH-112183)

Change '[2]' to '[1]' to get second argument.
(cherry picked from commit 8cd70ee)

Co-authored-by: Terry Jan Reedy <[email protected]>

Author: terryjreedy

Doc/library/__main__.rst

@@ -227,7 +227,7 @@ students::
     import sys
     from .student import search_students
 
-    student_name = sys.argv[2] if len(sys.argv) >= 2 else ''
+    student_name = sys.argv[1] if len(sys.argv) >= 2 else ''
     print(f'Found student: {search_students(student_name)}')
 
 Note that ``from .student import search_students`` is an example of a relative