[libsigcplusplus/libsigc++-2-10] slot: Document older syntax as deprecated

[Murray Cumming <murrayc src gnome org>]

commit d29b0ef0db248e180a00f62b3c0d458ce5992b2e
Author: Murray Cumming <murrayc murrayc com>
Date:   Sat Mar 12 17:45:47 2016 +0100

    slot: Document older syntax as deprecated

 sigc++/functors/macros/slot.h.m4 |   13 ++++++++++++-
 1 files changed, 12 insertions(+), 1 deletions(-)
---
diff --git a/sigc++/functors/macros/slot.h.m4 b/sigc++/functors/macros/slot.h.m4
index e0cf8c6..f57083f 100644
--- a/sigc++/functors/macros/slot.h.m4
+++ b/sigc++/functors/macros/slot.h.m4
@@ -185,7 +185,12 @@ FOR(1,$1,[
  *
  * sigc::slot<> is similar to std::function<>. If you're going to assign the
  * resulting functor to a sigc::slot or connect it to a sigc::signal, it's better
- * not to use std::function. It would become un unnecessary extra wrapper.
+ * not to use std::function. It would become an unnecessary extra wrapper.
+ *
+ * @deprecated Please use the syntax similar to that used by std::function<>:
+ * @code
+ * sigc::slot<void(bool, int)> some_slot;
+ * @endcode
  *
  * @ingroup slot
  */
@@ -197,6 +202,12 @@ class slot],[dnl
  * This is the template specialization of the unnumbered sigc::slot
  * template for $1 argument(s), specialized for different numbers of arguments
  * This is possible because the template has default (nil) template types.
+ *
+ * @deprecated Please use the syntax similar to that used by std::function<>:
+ * @code
+ * sigc::slot<void(bool, int)> some_slot;
+ * @endcode
+ *
 dnl *
 dnl * @ingroup slot
  */