[DOC] Query insights grouping documentation update

[dzane17]

What do you want to do?

• Request a change to existing documentation
• Add new documentation
• Report a technical problem with the documentation
• Other

Tell us about your request. Provide a summary of the request.
On page https://docs.opensearch.org/latest/observing-your-data/query-insights/grouping-top-n-queries/, top_queries.query_hashcode should be top_queries.query_group_hashcode

Version: List the OpenSearch version to which this issue applies, e.g. 2.14, 2.12--2.14, or all.
3.6

What other resources are available? Provide links to related issues, POCs, steps for testing, etc.