Hi Fintan,
As per the given description, I've added the required notes under the readlock and doneFileName options.
Kindly go through the content and let me know if my understanding is correct.

Updated doc link:

http://jenkinscat.gsslab.pnq.redhat.com:8080/job/doc-Fuse-6-2-1/lastStableBuild/artifact/publican/Apache_Camel_Component_Reference/tmp/en-US/html-single/index.html#IDU-File2

Also, we do have information about the Using done files and Writing done files in the Apache Camel Component Guide.
Let me know if I need to modify anything in these existing topics.

http://jenkinscat.gsslab.pnq.redhat.com:8080/job/doc-Fuse-6-2-1/lastStableBuild/artifact/publican/Apache_Camel_Component_Reference/tmp/en-US/html-single/index.html#IDU-File2