described headers in docs; added move in operator>>

doc/24_ref_optional_fwd.qbk

@@ -0,0 +1,32 @@
+[/
+    Boost.Optional
+
+    Copyright (c) 2003-2007 Fernando Luis Cacciola Carballal
+    Copyright (c) 2015 Andrzej Krzemienski
+
+    Distributed under the Boost Software License, Version 1.0.
+    (See accompanying file LICENSE_1_0.txt or copy at
+    http://www.boost.org/LICENSE_1_0.txt)
+]
+
+[section Header <boost/optional/optional_fwd.hpp>]
+
+[section Synopsis]
+```
+namespace boost {
+
+template <class T> class optional ;
+
+template <class T> void swap ( optional<T>& , optional<T>& );
+
+template <class T> struct optional_swap_should_use_default_constructor ;
+  
+} // namespace boost
+```
+
+This header only contains declarations.
+
+[endsect]
+
+
+[endsect]