(DOCS-16412) minDistance and maxDistance can be expressions (#5203)

* (DOCS-16412) minDistance and maxDistance can be expressions

* Includes changes from tech review

Author: sarahsimpers

source/reference/operator/aggregation/geoNear.txt

@@ -99,7 +99,10 @@ Definition
 
         - Optional. The maximum distance from the center point that the documents *can*
           be. MongoDB limits the results to those documents that fall within
-          the specified distance from the center point.
+          the specified distance from the center point. Starting in 
+          version 7.2, you can specify a valid constant
+          :ref:`expression <aggregation-expressions>` that resolves to
+          a number.
 
           Specify the distance in meters if the specified point is
           :term:`GeoJSON` and in radians if the specified point is
@@ -112,7 +115,10 @@ Definition
 
         - Optional. The minimum distance from the center point that the documents *can*
           be. MongoDB limits the results to those documents that fall outside
-          the specified distance from the center point.
+          the specified distance from the center point. Starting in 
+          version 7.2, you can specify a valid constant
+          :ref:`expression <aggregation-expressions>` that resolves to
+          a number.
 
           Specify the distance in meters for GeoJSON data and in radians for
           legacy coordinate pairs.