DOCSP-38949 Update broken links (mongodb#538)

Author: jordan-smith721

source/upgrade.txt

@@ -442,9 +442,5 @@ Version 4.8 Server Release Support Changes
 
 - The v4.8 driver drops support for {+mdb-server+} v3.4 and earlier.
   To use the v4.8 driver, your {+mdb-server+} must be v3.6 or later. To learn
-  how to upgrade your {+mdb-server+} to v3.6, follow the link that corresponds
-  to your MongoDB deployment configuration:
-
-  - :ref:`<3.6-upgrade-replica-set>`
-  - :ref:`<3.6-upgrade-standalone>`
-  - :ref:`<3.6-upgrade-sharded-cluster>`
+  how to upgrade your {+mdb-server+} deployment, see :manual:`Release
+  Notes </release-notes>` in the {+mdb-server+} manual.