boost.xml:

  - Added BoostBook documentation
  - Added Caramel concept documentation


[SVN r21177]

doc/src/boost.xml

@@ -780,4 +780,6 @@
   </library>
 
   <xi:include href="../../libs/variant/doc/variant.xml"/>
+  <xi:include href="../../tools/boostbook/doc/boostbook.xml"/>
+  <xi:include href="../../libs/concept_check/doc/reference/concepts.xml"/>
 </boostbook>