DOCSP-12378: add more descriptive text to clarify compatibility tables (#682)

Author: Chris Cho

source/about-compatibility.txt

@@ -28,13 +28,19 @@ The check marks (✓) indicate that the driver can access **all the
 features** of that specific version of MongoDB server unless those features
 have been deprecated or removed.
 
-If you are upgrading your server or driver version, you can use this table
-to identify which version of the driver you need to access all the newest
-features included in that version of the server.
-
-We recommend that you use the latest driver version that supports your
-server version. We also recommend that you avoid using older versions of
-the drivers that do not appear on the chart because they are unsupported.
+If you are **upgrading your server version**, your current driver should
+continue to function properly, but may not be able to access the features
+introduced in the newer server versions. We recommend using the newest
+compatible driver when upgrading your server version.
+
+If you are **upgrading your driver version**, you can use the table to
+identify which version you need to access all the newest features included
+in a specific version of the server. Also note that any of the minor
+or patch versions share the same compatibility as the major version
+release.
+
+We recommend that you avoid using older versions of the drivers that do not
+appear on the chart because they are unsupported.
 
 .. note::