For instance, sometimes Google search returns a page from version 7.9. A big banner at the top of the page prompts the user to click the link and see the latest version of the page. However, clicking this link or changing the dropdown from 7.9 to 8.1 just returns you to the main Intro page on the user manual.

This leaves the user with two options: search for the page they were just on in the correct version (slow, but accurate), or they could hit the browser back button and possibly get incorrect information (fast, but possibly inaccurate). The best option would be to redirect to the same page the user was on, or possibly a search results page based off the title of the page the user left.