Document that the new alternative syntax for string literals can break comments.

git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@14698 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02

Author: alainfrisch

Changes

@@ -7,6 +7,7 @@ Language features:
 - Attributes and extension nodes
 - Generative functors
 - Module aliases
+* Alternative syntax for string literals {id|...|id} (can break comments)
 
 Build system for the OCaml distribution:
 - Use -bin-annot when building.