Add a way to see recently viewed pages

[phillipskevin]

During user testing, multiple users had trouble getting back to documentation they had just been reading. It would be nice if we had a "Recent Pages" or "Recently Viewed" sidebar that would show the last handful of pages that you've read.

Here is an example flow where this would have been useful.

1. User is on the API docs page
2. User wants to read more about StacheElement
3. User sees "lifecycle methods" in the sidebar and clicks through to initialize, connectedCallback, and connect
4. User wants to see a more advanced example that uses connect and clicks Guides
5. User clicks on the CTA Bus Map guide
6. User reads through some of the guide and sees it is using connected() {} here
7. User wants to go back to the connect API docs they were just reading to see if this is the same thing, but can't find where they were reading about connect

[chasenlehara]

Do you remember the other user’s flow where this would’ve been useful? I’m wondering if there is some bigger issue that we should fix.