Issue #27178: Fix markup in tutorial

Patch by Nathan Harold.
diff --git a/Doc/tutorial/interpreter.rst b/Doc/tutorial/interpreter.rst
index 215af03..c89fae3 100644
--- a/Doc/tutorial/interpreter.rst
+++ b/Doc/tutorial/interpreter.rst
@@ -1,4 +1,4 @@
-3.6.. _tut-using:
+.. _tut-using:
 
 ****************************
 Using the Python Interpreter