That's a bit heavy in my opinion.  I don't think it's necessary to define in detail what "backward-compatibile" means, it's probably enough to say that whatever code might be running before the patch should keep running fine even after.  Bug fixes can change the behavior -- but only if the current behavior is clearly wrong.

In addition you might want to define the meaning of "features", "bug fixes", and "security fixes", mention what releases accept what, say that doc fixes are usually fine in bug fix releases too, and possibly document the deprecation process.  But maybe this is getting out of the initial scope of the issue :)