DOCSP-35949: write operations - upsert

[ccho-mongodb]

JIRA - https://jira.mongodb.org/browse/DOCSP-35949
Staging - https://preview-mongodbcchomongodb.gatsbyjs.io/laravel/DOCSP-35949-write-operations-upsert/fundamentals/write-operations/#update-or-insert-in-a-single-operation

Note:

This contains updates to the insert documents section (added new fields to the sample doc) and builds upon the Modify documents PR(#2808).

The third of three tickets to document the update operations is Update arrays

Checklist

• Add tests and ensure they pass
• Add an entry to the CHANGELOG.md file
• Update documentation for new features