Missing migration information

When moving our project to 2.x I discovered by way of it not behaving as expected, that the old way to specify variables used for the paths no longer works. Because Tomcat by default outputs our webapp logs wherever the current working directory is when launched, we set-up our file names like this "${catalina.base}/logs/mail.log".

However the old syntax no longer works and must now be used as "${sys:catalina.base}/logs/mail.log".
You should add some note in the migration page for that.