x/pkgsite: Examples are missing the "Output:" label when example output provided

[AdRiley]

What is the URL of the page with the issue?

https://pkg.go.dev/strings#example-Compare

What is your user agent?

Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:84.0) Gecko/20100101 Firefox/84.0

Screenshot

What did you do?

Went to the page

What did you expect to see?

The example output labelled as Output: as it is on GoDoc.

Without the label it isn't immediately clear what you are looking at.

What did you see instead?

There is no "Output:" label instead the example code and example output are just right next to each other.

[AdRiley]

I would like to fix this if that would be OK?

[julieqiu]

/cc @georgehu for UX input