exception_ptr improvements, documentation update.

[SVN r52981]

doc/types.html

@@ -26,6 +26,8 @@
 <p><a href="error_info_value_type.html">error_info::value_type</a></p>
 <p><a href="exception.html">exception</a></p>
 <p><a href="exception_ptr.html">exception_ptr</a></p>
+<h3>o</h3>
+<p><a href="original_exception_type.html">original_exception_type</a></p>
 <h3>u</h3>
 <p><a href="unknown_exception.html">unknown_exception</a></p>
 </div>