Remove outdated Shibboleth page from docs
Problem to solve
This page says it's for installs 9.x and older: https://docs.gitlab.com/ee/integration/shibboleth.html
Proposal
Remove the page.
Not sure if we'd put a redirect in since this is kind of a weird one because it's more like we forgot to remove it in 12.0.
Who can address the issue
technical writer