Update aggregation.txt

(cherry picked from commit d49ce16)

Author: rustagir

source/fundamentals/aggregation.txt

@@ -27,10 +27,6 @@ This guide includes the following sections:
 - :ref:`Compare Aggregation and Find Operations <rust-agg-compare>`
   describes the functionality differences between aggregation and find operations
 
-- :ref:`Retrieve Documents as an Array <rust-cursor-array>`
-  describes how to access all results as a single array by collecting the
-  returned cursor results
-
 - :ref:`Server Limitations <rust-agg-limitations>` describes the
   server limitations on memory usage for aggregation operations
 
@@ -262,4 +258,4 @@ To learn more about any of the methods or types discussed in this
 guide, see the following API documentation:
 
 - `aggregate() <{+api+}/struct.Collection.html#method.aggregate>`__
-- `AggregateOptions <{+api+}/options/struct.AggregateOptions.html>`__
+- `AggregateOptions <{+api+}/options/struct.AggregateOptions.html>`__