documentation. Patch and log message graciously provided by David
Summers <david@...>.
* doc/book/book/ch03.xml : Grammar fix.
* doc/book/book/ch04.xml : Make example match commentary.
* doc/book/book/ch05.xml : Grammar fix.
* doc/book/book/ch07.xml : Grammar fix. Authentication data is no longer
stored in the .svn/auth working copy directories.
* doc/book/book/ch08.xml : Fix typo on "Revision".
Take out "+" in example prompt and program response.