Added language to reflect the intended behavior for triple-quoted typ…

…e annotation expressions.

docs/spec/annotations.rst

@@ -114,6 +114,16 @@ be evaluated.
 Moreover, the expression should be parseable as a valid type hint, i.e.,
 it is constrained by the rules from the section on :ref:`valid-types`.
 
+If a triple quote is used, the string should be parsed as though it is
+implicitly surrounded by parentheses. This allows newline characters to be 
+used within the string literal.
+
+  value: """
+      int |
+      str |
+      list[Any]
+    """
+
 It is allowable to use string literals as *part* of a type hint, for
 example::