404 Not Found Reference Doc.

[mrksph]

Describe the bug
Missing 4.0 reference doc. Currently it's retuning 404 Not Found

https://docs.spring.io/spring-session/reference/4.0/index.html

To Reproduce
Enter https://docs.spring.io/spring-session/reference/4.0/index.html

Expected behavior
I expect to see the 4.0 Reference doc

[mrksph]

@vpavic @rwinch @eleftherias ??

[mrksph]

@jzheaux

[rwinch]

Thanks for the issue @mrksph This is now fixed