This is an example of what you could say in your update txt doc
As you can see I have this on my server, and can change it per version update.
All versions that update to will see the most current update notes, and they
will also always download the latest release only. 
Meaning: If your new version is 1.5 (as mine is)
	 then a person with v 1.1 will be updating to v 1.5
	 and a person with v 1.4 will also be updating to v 1.5

Make sense??