* doc/book/book/appa.xml
Remove extraneous spaces before and after mark-up.
Fix mark-up: change some instances of <command> to <literal>.
* doc/book/book/appb.xml
Capitalise 'Apache'.
Fix mark-up: change some instances of <filename> to <command>.
* doc/book/book/appc.xml
s/svn/Subversion/
* doc/book/book/ch03.xml
Remove an obsolete comment in the XML source.
Remove extraneous spaces before and after mark-up.
* doc/book/book/ch04.xml
Remove an obsolete comment in the XML source.
Capitalise 'URLs'.
Remove extraneous spaces before and after mark-up.
* doc/book/book/ch06.xml
Fix mark-up of some instances of <command>, <filename>, <literal>.
* doc/book/book/ch09.xml
Remove extraneous spaces before and after mark-up.
s/svn/Subversion/
Fix mark-up of some instances of <command>, <filename>, etc.
