Add issue about order of onException and transacted at route level to known issues in the docs

Hi

See DEV-3597

If you have a Java DSL route such as

from("activemqjta:queue:testtt")
.routeId("testtt")
.transacted("requiredJta")
.onException(Exception.class)
...

Then you must configure onException at first, eg before .transacted. So they should be swapped like

from("activemqjta:queue:testtt")
.routeId("testtt")
.onException(Exception.class)
...
.transacted("requiredJta")

Can this issue be added to the known issues part of the Fuse MR documentation
http://fusesource.com/docs/router/2.8/migration/Known.html