Add the 'Add your own extension' button in Grafana k6 docs

[joanlopez]

Looks like the new Grafana docs site (https://grafana.com/docs/k6/latest/extensions/explore/) is missing the Add your own extension button (see the image below) that exists in the analogous site in the former k6 docs (https://k6.io/docs/extensions/get-started/explore/). Or at least I cannot find it 😅

So, would be nice to either add it (if not present) or make it as visible as it is in k6 docs.

Thanks!

PS: The button 👇🏻