PEP 484: Add a note that misplaced type comments are errors for typecheckers (#133)

Fixes python/typing#210.

This behaviour with --fast-parser is in mypy since mid-May. It looks like nobody is complaining.

pep-0484.txt

@@ -2027,6 +2027,17 @@ Notes:
     def add(a, b):  # type: (int, int) -> int
         return a + b
 
+- Misplaced type comments will be flagged as errors by a type checker.
+  If necessary, such comments could be commented twice. For example::
+
+    def f():
+        '''Docstring'''
+        # type: () -> None # Error!
+
+    def g():
+        '''Docstring'''
+        # # type: () -> None # This is OK
+
 
 Rejected Alternatives
 =====================