DOCS-14133 new dateAdd, dateSubtract agg expressions

Author: mungitoperrito

source/includes/extracts-agg-operators.yaml

@@ -379,6 +379,10 @@ content: |
       * - Name
         - Description
 
+      * - :expression:`$dateAdd`
+
+        - Adds a number of time units to a date object.
+
       * - :expression:`$dateDiff`
 
         - Returns the difference between two dates.
@@ -392,6 +396,10 @@ content: |
 
         - Converts a date/time string to a date object.
 
+      * - :expression:`$dateSubtract`
+
+        - Subtracts a number of time units from a date object.
+
       * - :expression:`$dateToParts`
 
         - Returns a document containing the constituent parts of a date.

source/includes/fact-timezone-description-no-option.rst

@@ -1,4 +1,4 @@
-The timezone of the operation result. ``<tzExpression>`` must be a 
+The timezone to carry out the operation. ``<tzExpression>`` must be a
 valid :ref:`expression <aggregation-expressions>` that resolves to a
 string formatted as either an `Olson Timezone Identifier
 <https://en.wikipedia.org/wiki/List_of_tz_database_time_zones>`_ or a

source/reference/mongodb-extended-json.txt

@@ -75,6 +75,8 @@ MongoDB Database Tools
 
 .. include:: /includes/extracts/4.2-changes-extended-json-v2.rst
 
+.. _bsontype-list-of-types:
+
 BSON Data Types and Associated Representations
 ----------------------------------------------
 

source/reference/operator/aggregation.txt

@@ -312,6 +312,10 @@ Alphabetical Listing of Expression Operators
      - Returns the hyperbolic cosine of a value that is measured in
        radians.
 
+   * - :expression:`$dateAdd`
+
+     - Adds a number of time units to a date object.
+
    * - :expression:`$dateDiff`
 
      - Returns the difference between two dates.
@@ -321,6 +325,9 @@ Alphabetical Listing of Expression Operators
      - Constructs a BSON Date object given the date's constituent
        parts.
 
+   * - :expression:`$dateSubtract`
+
+     - Subtracts a number of time units from a date object.
 
    * - :expression:`$dateToParts`
 
@@ -1011,8 +1018,10 @@ Alphabetical Listing of Expression Operators
    /reference/operator/aggregation/convert
    /reference/operator/aggregation/cos
    /reference/operator/aggregation/cosh
-   /reference/operator/aggregation/dateDiff   
+   /reference/operator/aggregation/dateAdd
+   /reference/operator/aggregation/dateDiff
    /reference/operator/aggregation/dateFromParts
+   /reference/operator/aggregation/dateSubtract
    /reference/operator/aggregation/dateToParts
    /reference/operator/aggregation/dateFromString
    /reference/operator/aggregation/dateToString