Just for the record:
I can't recall exactly, but isn't viewing the "readme" file an option at the end of the installation process?
Apparently not.
I took a test system (W7-64 if it matters), uninstalled MA3, used Regedit to remove all mentions of SereneScreen from the registry.
Rebooted to make sure, verified that there was nothing in the Programs, or in my Appdata.
Downloaded a fresh copy of the .exe from SereneScreen.com, and installed it.
It did require me to enter my registration code (presumably demonstrating that it was a fresh install).
There was no display of the readme.txt file, and no question asking if I wanted to see it, nor any indication of where it might be found.