Update scripting documentation for Java Api

[ericsnx]

Hello, can someone envolved in the scripting and java api part update the documentation below?

https://www.elastic.co/guide/en/elasticsearch/client/java-api/current/indexed-scripts.html

as you can see above, it's very outdated, right now it's barely impossible to use this documentation since everything have changed, I would love to contribute with such change but actually I can't even make my own piece of code to insert a painless script on my cluster work.

What I'm missing it's basic examples about how to store painless scripts using the java api.

[javanna]

@jdconrad can you have a look please?

[jdconrad]

@javanna Will do.

[jdconrad]

Going to close this in favor of #23777