[DOCS] Link to the Painless Lab in the "Painless Debugging" page

[Ronserruya]

The painless debugging page (https://www.elastic.co/guide/en/elasticsearch/painless/current/painless-debugging.html) States that "Painless doesn’t have a REPL and while it’d be nice for it to have one day", while the Painless Lab is not a full REPL it's an excellent tool that provides a huge upgrade from the methods on that page.

I only found about the Painless Lab when I accidentally used a Kibana version that's newer than what we use in our org, and I've been using it almost daily since, it's a shame that it's hidden in the docs like this.

TL;DR Link to https://www.elastic.co/guide/en/kibana/master/painlesslab.html on https://www.elastic.co/guide/en/elasticsearch/painless/current/painless-debugging.html

Thanks again for all of the work on the lab ❤️

[elasticmachine]

Pinging @elastic/es-docs (Team:Docs)

[elasticmachine]

Pinging @elastic/es-core-infra (Team:Core/Infra)

[cjcenizal]

Thanks so much for creating this issue @Ronserruya! Your kind words mean a lot to us. Great suggestion to improve visibility of Painless Lab -- we will get on this.

[lockewritesdocs]

Thanks for opening this issue @Ronserruya! I'm currently reworking the docs for how to use scripts so that they focus on teaching users how to write scripts in Painless. I'll make sure to explore and incorporate the Painless Lab 👍