[docs] improve UPDATING.md around 0.31's [now] optional deps

UPDATING.md

@@ -22,17 +22,24 @@ This file documents any backwards-incompatible changes in Superset and
 assists people when migrating to a new version.
 
 ## Superset 0.32.0
-* If you use `Hive` or `Presto`, we've moved some dependencies that were
-  in the main package as optional now. To get these packages,
-  run `pip install superset[presto]` and/or `pip install superset[hive]` as
-  required.
 
 * [5445](https://github.com/apache/incubator-superset/pull/5445) : a change 
 which prevents encoding of empty string from form data in the datanbase. 
 This involves a non-schema changing migration which does potentially impact
 a large number of records. Scheduled downtime may be advised.
 
 ## Superset 0.31.0
+
+* If you use `Hive` or `Presto`, we've moved some dependencies that were
+  in the main package as optional now. To get these packages,
+  run `pip install superset[presto]` and/or `pip install superset[hive]` as
+  required.
+
+* Similarly, if you use Celery's `flower`, `gsheetsdb`, `thrift` or
+  `thrift-sasl`, those dependencies have now been made optional in our
+  package, meaning you may have to install them in your environment post
+  0.31.0
+
 * boto3 / botocore was removed from the dependency list. If you use s3
 as a place to store your SQL Lab result set or Hive uploads, you may
 have to rely on an alternate requirements.txt file to install those