DOCS-4120: minor typo

Signed-off-by: Sam Kleinman <samk@10gen.com>

Author: devkev

source/reference/operator/aggregation/geoNear.txt

@@ -50,7 +50,7 @@ When using :pipeline:`$geoNear`, consider that:
   the documents hold the coordinate pair or point. Because
   :pipeline:`$geoNear` requires that the collection have a single
   geospatial index, :pipeline:`$geoNear` implicitly uses the indexed
-  the field.
+  field.
 
 - If using a :doc:`2dsphere index </core/2dsphere>`, you must specify
   ``spherical: true``.