Cosmos Spark connector: Ingestion scenario best practices (Azure#26160)

* Documentation skeleton

* Update Ingestion.md

* Update Ingestion.md

* Update Ingestion.md

* Iterating on ingestion best practices

* Update Ingestion.md

* Update Ingestion.md

* Update Ingestion.md

* Iterating on ingestion best-practices

* Fixing build analysis error regarding relative link

* Maxing link absolute

* Reacting to code review feedback

* Fixing link format

* Reacting to code review feedback

* Update Ingestion.md

* Moving the checklist up

* Merging and reacting to some offline feedback

* Update Ingestion.md

Author: FabianMeiswinkel