Fix some links in the optional docs. Refs #1687

[SVN r44592]

doc/Jamfile.v2

@@ -26,5 +26,8 @@ boostbook standalone
         <xsl:param>toc.max.depth=2
         <xsl:param>toc.section.depth=2
         <xsl:param>chunk.section.depth=1
+        <xsl:param>boost.root=../../../..
+        <xsl:param>boost.libraries=../../../libraries.htm
+        <xsl:param>html.stylesheet=../../../../doc/html/boostbook.css
     ;
 

doc/optional.qbk

@@ -22,7 +22,7 @@ Distributed under the Boost Software License, Version 1.0.
 [/ Cited Boost resources ]
 
 [def __BOOST_VARIANT__ [@../../../variant/index.html Boost.Variant]]
-[def __BOOST_TRIBOOL__ [@../../../tribool/index.html boost::tribool]]
+[def __BOOST_TRIBOOL__ [@../../../../doc/html/tribool.html boost::tribool]]
 
 [def __OPTIONAL_POINTEE__ [@../../../utility/OptionalPointee.html OptionalPointee]]
 [def __COPY_CONSTRUCTIBLE__ [@../../../utility/CopyConstructible.html Copy Constructible]]