Update URL of legacy pre-built artifacts

The cars.uchicago.edu areaDetector URL currently redirects to the GitHub
areaDetector repository instead of the previously provided page. Update
the URL so that it is consistent with the existing text.

Author: henriquesimoes

RELEASE.md

@@ -9,7 +9,7 @@ https://github.com/areaDetector/ADCore.
 
 Tagged source code and pre-built binary releases prior to R2-0 are included
 in the areaDetector releases available via links at
-https://cars.uchicago.edu/software/epics/areaDetector.html.
+https://areadetector.github.io/areaDetector/legacy_versions.html.
 
 Tagged source code releases from R2-0 onward can be obtained at
 https://github.com/areaDetector/ADCore/releases.