DOCSP-35937 aggregations builder 4.3 (#2876)

* DOCSP-35937: aggregation builder page

Author: Chris Cho

docs/fundamentals.txt

@@ -18,10 +18,12 @@ Fundamentals
    /fundamentals/database-collection
    /fundamentals/read-operations
    /fundamentals/write-operations
+   /fundamentals/aggregation-builder
 
 Learn how to use the {+odm-long+} to perform the following tasks:
 
 - :ref:`Manage Databases and Collections <laravel-db-coll>`
 - :ref:`Read Operations <laravel-fundamentals-read-ops>`
 - :ref:`Write Operations <laravel-fundamentals-write-ops>`
+- :ref:`Create Aggregation Pipelines by Using the Aggregation Builder <laravel-aggregation-builder>`