(DOCSP-21416-fix) Fix required versions (#98)

Author: zach-carr

source/includes/list-prerequisites.rst

@@ -2,6 +2,6 @@
   :manual:`MongoDB documentation </>` and `Spark documentation
   <https://spark.apache.org/docs/latest/>`_ for more details.
 
-- Running MongoDB instance (version 3.6 or later).
+- Running MongoDB instance (version 4.0 or later).
 
-- Spark 3.2.x.
+- Spark version 3.1 or later

source/index.txt

@@ -41,8 +41,8 @@ versions of Apache Spark and MongoDB:
      - MongoDB Version
 
    * - **{+current-version+}**
-     - **3.2.x**
-     - **3.6 or later**
+     - **3.1 or later**
+     - **4.0 or later**
 
 Announcements
 -------------