[DOC] More explicit doc for faceted navigation

[smacrakis]

What do you want to do?

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

Tell us about your request. Provide a summary of the request and all versions that are affected.

We currently only mention faceted navigation in one place -- https://opensearch.org/docs/latest/aggregations/bucket/index/ -- and don't give users any guidance on how to use bucket aggregations to implement faceted search.

It might be good to have a section called Faceted Navigation discussing what faceted search is and how to code it.

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

[hdhalter]

Thanks, Stavros! We have an existing issue here: #2157. I will close this in favor of that one.