$search aggregation pipleline stage performs a full-text search of
the field or fields in an Atlas collection. The fields must be covered
by an Atlas Search index. See:
Index Definitions to learn more about creating and managing Atlas Search indexes.
Atlas Search Aggregation Pipeline Stages to learn more about the
$searchpipeline stage syntax and usage.
$search Operators to learn more about the
$searchaggregation pipeline stage operators.
$search aggregation pipeline stage is only available for
collections hosted on MongoDB Atlas cluster tiers
running MongoDB version 4.2 or later. To learn more, see