Merge intrusive documentation fixes.

Merged revisions 50755 via svnmerge from 
https://svn.boost.org/svn/boost/trunk

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  r50755 | danieljames | 2009-01-24 16:53:03 +0000 (Sat, 24 Jan 2009) | 3 lines
  
  Documentation fixes for intrusive: restore the reference documentation and fix
  some spelling mistakes.
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[SVN r50777]

libs/intrusive

@@ -1 +1 @@
-Subproject commit 5a06bad196f75c9e72d2584b16bd71007318d75f
+Subproject commit c1f7a166109ad634d9f4c25e3551e2ec47f393c8