The normal place you'd find the release notes for is under the platform itself rather than the code release, though it depends and isn't consistent. Some release notes are organized by software rather than platform. ED means early deployment.
The release you're mentioning is probably a bugfix release for Cisco 3700 switches. That information is here:
Typically, you'll look at the main release for the caveats, then follow the train down the bugfix releases. Usually, a bug scrub is also helpful, e.g. searching the features you're deploying using the Cisco bugsearch tools to determine whether any of them are things you might be concerned about.
Your Cisco or VAR SEs can also assist in choosing the right release for your needs.