As you may have noticed, we've revamped the design for docs.oracle.com. While the new look and feel lets us present information for a lot of products in a clearer (and snazzier) format, it also means that the path to the Ops Center docs from the main page is different.
The new library front page has a set of icons for the various categories of documentation. To get to Ops Center, you'll click on the Enterprise Manager category.
This brings up the main page for Enterprise Manager software, which has a tab for Ops Center. You'll click that tab:
Then, once the tab is displayed, you'll click the version of Ops Center that you want:
It's worth noting that the urls for the Ops Center libraries haven't changed, so if you have them bookmarked you don't need to change anything. You can also still get to the library through the help button at the top of the Ops Center UI. This only affects how you get to those libraries through the landing page.