Fix broken link in documentation.

HP's web server has apparently become case-sensitive sometime recently.
Per bug #13479 from Daniel Abraham.  Corrected link identified by Alvaro.

doc/src/sgml/runtime.sgml

@@ -2105,7 +2105,7 @@ pg_dumpall -p 5432 | psql -d postgres -p 5433
    are also checked if the parameter <xref linkend="guc-ssl-crl-file"> is set.
    <!-- If this URL changes replace it with a URL to www.archive.org. -->
    (See <ulink
-   url="http://h71000.www7.hp.com/DOC/83final/BA554_90007/ch04s02.html"></>
+   url="http://h71000.www7.hp.com/doc/83final/ba554_90007/ch04s02.html"></>
    for diagrams showing SSL certificate usage.)
   </para>