Merge asio details from the release branch.

[SVN r47812]

doc/src/boost.xml

@@ -54,6 +54,18 @@
     <xi:include href="../../libs/any/doc/any.xml"/>
     <xi:include href="../../libs/array/doc/array.xml"/>
 
+   <library name="Asio" dirname="asio" html-only="1">
+     <libraryinfo>
+       <author>
+         <firstname>Christopher</firstname>
+         <surname>Kohlhoff</surname>
+       </author>
+
+       <librarypurpose>Portable networking, including sockets, timers, hostname resolution and socket iostreams.</librarypurpose>
+       <librarycategory name="category:io"/>
+     </libraryinfo>
+   </library>
+
    <library name="Bind" dirname="bind" html-only="1">
      <libraryinfo>
        <author>