Facet docs (#1178)

* document facet endpoint

* Update qdrant-landing/content/documentation/concepts/payload.md

Co-authored-by: Tim Visée <[email protected]>

* add go example

* Patch incorrect filter definition in Python example

* Specify minimum supported Qdrant version

* Add client examples

* Use proper indentation in C# examples

* make examples consistent

* make examples consistent

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Co-authored-by: David Myriel <[email protected]>
Co-authored-by: Tim Visée <[email protected]>
Co-authored-by: generall <[email protected]>