[libxml++] xmlpp::wrapped_exception: Add comments

[Kjell Ahlstedt <kjellahl src gnome org>]

commit 23a566f084d9c119524a401dd748f741e9380586
Author: Kjell Ahlstedt <kjell ahlstedt bredband net>
Date:   Thu Aug 27 17:15:33 2015 +0200

    xmlpp::wrapped_exception: Add comments
    
    Bug #753570

 libxml++/exceptions/wrapped_exception.h |   11 +++++++++++
 1 files changed, 11 insertions(+), 0 deletions(-)
---
diff --git a/libxml++/exceptions/wrapped_exception.h b/libxml++/exceptions/wrapped_exception.h
index 06b7808..6fa7bac 100644
--- a/libxml++/exceptions/wrapped_exception.h
+++ b/libxml++/exceptions/wrapped_exception.h
@@ -26,6 +26,17 @@ namespace xmlpp
 {
 
 #ifndef DOXYGEN_SHOULD_SKIP_THIS
+//TODO: At the next ABI break, consider changing
+//   exception* exception_;
+// to
+//   std::exception_ptr exception_ptr_;
+// in xmlpp::Parser and xmlpp::Validator, and removing xmlpp::wrapped_exception.
+
+/** Helper class for propagating an exception through C code.
+ * Should not be used by applications.
+ *
+ * @newin{2,40}
+ */
 class wrapped_exception : public exception
 {
 public: