examples are for v3.0 only

We should either produce examples only for 3.1, or for both 3.0 and 3.1. Perhaps when clicking on an individual example, there was a \[ 3.0 \| 3.1 \] toggle at the top of the page, defaulting to the latest version (currently 3.1)?

I can help translate the existing 3.0 examples to their equivalent 3.1 forms.