Fix a typo.
Fix a typo.

Suggested by: <rengmann@lycos.de>

* doc/book/book/ch03.xml
  (svn-ch-3-sect-5.2.1): Fix a typo.

jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion