* doc/ref/sxml.texi (SXML): Reorder and begin rewriting. Fix formatting
throughout, provide a new introduction, and the beginning of proper
SSAX documentation.
* doc/ref/sxml-match.texi:
* doc/ref/texinfo.texi:
* doc/ref/web.texi: Update references to new node names.
* doc/ref/statprof.texi:
* doc/ref/sxml.texi:
* doc/ref/texinfo.texi: New files, containing the documentation that was
previously generated from source and rendered into
standard-library.texi. The documentation is still horrible, but at
least now it is user-editable.
