How about a filter:
OpenGL 1.1 … 2.1
Extensions: Yes | No
Yes, I know it could be hard to mark all the differences in the text for use with some script. Especially that some extensions added something, others replaced some parts of specification - thet means we not only filter what pages to display, but also what information to display in them.
We also have to consider if such filter will really be useful and worth the effort, but if yes then why not?