In JDBC Pool changelog file:
- Add a note that this changelog file is obsolete.
- Add XSLT stylesheet reference so that the file is viewable in a web browser (such as Firefox).
- Fix a pair of markup errors.

It is backport of r1617576 from tomcat/trunk.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc7.0.x/trunk@1617578 13f79535-47bb-0310-9956-ffa450edef68