* doc/xml/manual/allocator.xml: Link to table documenting evolution
of extension allocators.
* doc/xml/manual/evolution.xml: Use angle brackets for header names.
Document new headers in 7.2, 8.1 and 9.1 releases.
* doc/xml/manual/using.xml: Adjust link target for new_allocator.
* doc/html/*: Regenerate.
From-SVN: r269794
