[Documentation] EC2 Guide - y versions are minor, not major

Appendix "A.1. Amazon EC2 AMIs for Red Hat Cloud Access Program", section "Maintenance of AMIs" says:

"New AMIs for the y releases (major releases) ..."

This should be: "New AMIs for the y releases (minor releases) ..."

The version format is: x.y.z, e.g. 7.1.0 (major, minor, micro).