Add missing reST target to one heading in the tutorial
diff --git a/Doc/tutorial/interpreter.rst b/Doc/tutorial/interpreter.rst
index df93af2..0cdba6e 100644
--- a/Doc/tutorial/interpreter.rst
+++ b/Doc/tutorial/interpreter.rst
@@ -166,6 +166,8 @@
 suppressed.
 
 
+.. _tut-source-encoding:
+
 Source Code Encoding
 --------------------