Tomcat 7 Minor Updates for 6.1.x

Added to User Guide's 6.1 errata explaining recommendation to add `support-tomcat.jar` file during Tomcat 7 installation. Also pointed out irrelevant note in regards to `ccpp.jar` file; the issue was fixed before release of Liferay 6.0.

https://issues.liferay.com/browse/LRDOCS-490