DOCSP-31653 Remove duplicate aggregation content (#4200)

* move pages around

* remove alphabetical list of stages

* remove alphabetical list of operators

* change header levels

* remove quick reference page

* fix broken refs

* add missing ref

* fix build errors

* fix build errors

* adjust page title

* update toc order

* fix ref link

* wording

* remove superfluous ref

* remove superfluous ref

* consistency

* remove superfluous ref

* fix git conflict

* edits

* fix ref

Author: jeff-allen-mongo

config/redirects

@@ -2553,3 +2553,6 @@ raw: https://mongodb.github.io/mongo-java-driver/ -> ${base}/drivers/java/sync/c
 
 # DOCSP-32407
 [v4.2-*]: ${prefix}/${version}/meta/aggregation-quick-reference/ -> ${base}/${version}/reference/aggregation-quick-reference/
+
+# DOCSP-31653
+[v7.0-*]: ${prefix}/${version}/reference/aggregation-quick-reference/ -> ${base}/${version}/reference/aggregation/

source/core/aggregation-pipeline.txt

@@ -160,7 +160,7 @@ Example output:
    - :doc:`/tutorial/aggregation-zip-code-data-set`
    - :doc:`/tutorial/update-documents-with-aggregation-pipeline`
 
-.. _aggregation-pipeline-stages:
+.. _aggregation-pipeline-stages-details:
 
 Additional Aggregation Pipeline Stage Details
 ---------------------------------------------
@@ -209,6 +209,22 @@ aggregation expressions in JavaScript.
 
 For all aggregation expressions, see :ref:`aggregation-expressions`.
 
+.. _agg-quick-ref-field-paths:
+
+Field Paths
+~~~~~~~~~~~
+
+Aggregation expressions use :term:`field path` to access fields in the
+input documents. To specify a field path, prefix the field name or the
+:ref:`dotted field name <document-dot-notation>` (if the field is in
+the embedded document) with a dollar sign ``$``. For example,
+``"$user"`` to specify the field path for the ``user`` field or
+``"$user.name"`` to specify the field path to ``"user.name"`` field.
+
+``"$<field>"`` is equivalent to ``"$$CURRENT.<field>"`` where the
+:variable:`CURRENT` is a system variable that defaults to the root of
+the current object, unless stated otherwise in specific stages.
+
 Run an Aggregation Pipeline
 ---------------------------
 

source/core/materialized-views.txt

@@ -70,7 +70,7 @@ steps:
 
       The aggregation stage transforms the data that you want to save as
       a view. To learn more about available aggregation stages, see 
-      :ref:`agg-pipeline-quick-ref`.
+      :ref:`aggregation-pipeline-operator-reference`.
 
       For this example, add a new field with the :pipeline:`$set` stage:
 

source/includes/extracts-agg-stages.yaml

@@ -316,14 +316,15 @@ content: |
         - Returns information on active and/or dormant operations for
           the MongoDB deployment.
 
+      * - :pipeline:`$documents`
+
+        - Returns literal documents from input values.
+
       * - :pipeline:`$listLocalSessions`
 
         - Lists all active sessions recently in use on the currently
           connected :binary:`~bin.mongos` or :binary:`~bin.mongod`
           instance. These sessions may have not yet propagated to the
           ``system.sessions`` collection.
-      
-      * - :pipeline:`$documents`
 
-        - Returns literal documents from input values.
 ...

source/includes/fact-use-aggregation-not-map-reduce.rst

@@ -5,8 +5,8 @@ deprecated:
   :ref:`aggregation pipeline <aggregation-pipeline>`. Aggregation
   pipelines provide better performance and usability than map-reduce.
 
-- You can rewrite map-reduce operations using :ref:`aggregation
-  pipeline stages <agg-pipeline-quick-ref>`, such as
+- You can rewrite map-reduce operations using :ref:`aggregation pipeline
+  stages <aggregation-pipeline-operator-reference>`, such as
   :pipeline:`$group`, :pipeline:`$merge`, and others. 
 
 - For map-reduce operations that require custom functionality, you can