Version Control With Subversion Source

finishes the change started in r8735.

* doc/book/book/appe.xml
(Repository Converters): New first section.
(ViewCVS): Renumber this section.
(SubWiki): Renumber this section.

* doc/book/book/appa.xml
(Converting a Repository from CVS to Subversion): New section, so
this topic shows up in the table of contents, but containing just
a reference to the new "Repository Converters" above.