This page has a link to release notes which is broken:
http://tools.jboss.org/downloads/devstudio/luna/8.0.2.GA.html

It points to https://access.redhat.com/site/documentation/en-US/Red_Hat_JBoss_Developer_Studio/8.0/html/Release_Notes_8.0.2/index.html

The same problem happens for JBDS 8.0.1 and 8.0.0.

The correct link is e.g.:
https://access.redhat.com/documentation/en-US/Red_Hat_JBoss_Developer_Studio/8.0/html/8.0.2_Release_Notes/

So it seems we just need to trim off the trailing index.html .