DOCSP-33931: fix agg operator links (#137)

* DOCSP-33931: fix broken links to server manual docs

(cherry picked from commit 8c0a34aa8f542b50ce515ea177c2adb909dad0ac)
(cherry picked from commit 6943c81)

Author: Chris Cho

source/fundamentals/aggregation-expression-operations.txt

@@ -302,13 +302,13 @@ using the methods described in this section.
      - :manual:`$filter </reference/operator/aggregation/filter/>`
 
    * - `first() <{+api+}/apidocs/mongodb-driver-core/com/mongodb/client/model/mql/MqlArray.html#first()>`__
-     - :manual:`$first </reference/operator/aggregation/first-array-element/>`
+     - :manual:`$first </reference/operator/aggregation/first/>`
 
    * - `joinStrings() <{+api+}/apidocs/mongodb-driver-core/com/mongodb/client/model/mql/MqlArray.html#joinStrings(java.util.function.Function)>`__
      - :manual:`$concat </reference/operator/aggregation/concat/>`
 
    * - `last() <{+api+}/apidocs/mongodb-driver-core/com/mongodb/client/model/mql/MqlArray.html#last()>`__
-     - :manual:`$last </reference/operator/aggregation/last-array-element/>`
+     - :manual:`$last </reference/operator/aggregation/last/>`
 
    * - `map() <{+api+}/apidocs/mongodb-driver-core/com/mongodb/client/model/mql/MqlArray.html#map(java.util.function.Function)>`__
      - :manual:`$map </reference/operator/aggregation/map/>`
@@ -1117,4 +1117,4 @@ the Query API:
                     then: "$rating",
                     else: 1
            } }
-   } } ]
+   } } ]