SOLR-18100: Improve Combined Query Feature documentation

[ilariapet]

https://issues.apache.org/jira/browse/SOLR-18100

Description

Some sections of the Combined Query Feature documentation have been made clearer to improve understanding and usability of the feature.

Checklist

Please review the following and check all that apply:

• I have reviewed the guidelines for How to Contribute and my code conforms to the standards described there to the best of my ability.
• I have created a Jira issue and added the issue ID to my pull request title.
• I have given Solr maintainers access to contribute to my PR branch. (optional but recommended, not available for branches on forks living under an organisation)
• I have developed this patch against the main branch.
• I have run ./gradlew check.
• I have added tests for my changes.
• I have added documentation for the Reference Guide
• I have added a changelog entry for my change

[alessandrobenedetti]

The documentation change is interesting and needs some minor changes

[dsmiley]

thanks for contributing!

CC @ercsonusharma

[ercsonusharma]

I haven’t encountered this issue before, as it might vary depending on the infrastructure (?)

[ilariapet]

I tested this feature while preparing a tutorial blog post (an end-to-end walkthrough explaining how to use it). I ran everything locally. When I used Solr in standalone mode and executed the combined query, I received the error. Could you please try to reproduce it on your side?

[ercsonusharma]

It’s better to mention it IMO, provided you can replicate it.

[ilariapet]

@dsmiley, @ercsonusharma and @alessandrobenedetti Thank you very much for the review.