Fix doc-string examples that were corrupted by r13678.
Fix doc-string examples that were corrupted by r13678.

* subversion/include/svn_opt.h
  (svn_opt_parse_path): Restore the "@" signs to how they used to be, using
    quotes to make Doxygen happy.  (In particular, one example intentionally
    had a double "@" in it originally.)

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