Revert "Document Sync breaking change in 5.9.x (#398)"

This reverts commit c475523.

UPGRADE.md

@@ -3,43 +3,6 @@
 _After `5.0.0` all `MINOR` and `MAJOR` version bumps will have upgrade notes
 posted here._
 
-[2017-11-XX] 5.8.x to 5.9.x
----------------------------
-
-### CHANGED - Make `data` an optional parameter on Sync Document/List Item/Map Item update.
-
-#### Rationale
-This was changed to add support for time-to-live to Sync objects. Users can now either provide either `data`, `ttl`, or both.
-This only affects users who pass the `twilioRestClient` parameter to the _Affected Resources_ below.  
-
-#### Affected Resources
-- DocumentResource.Update(...)
-- SyncListItemResource.Update(...)
-- SyncMapItemResource.Update(...)
-
-#### 5.8.x
-```cs
-using Twilio.Rest.Sync.V1.Service;
-using Twilio.Rest.Sync.V1.Service.SyncList;
-using Twilio.Rest.Sync.V1.Service.SyncMap;
-
-DocumentResource.Update("IS123", "ET123", "{}", twilioRestClient);
-SyncListItemResource.Update("IS123", "ES123", 1, "{}", twilioRestClient);
-SyncMapItemResource.Update("IS123", "MP123", "myKey" "{}", twilioRestClient);
-```
-
-#### 5.9.x
-```cs
-using Twilio.Rest.Sync.V1.Service;
-using Twilio.Rest.Sync.V1.Service.SyncList;
-using Twilio.Rest.Sync.V1.Service.SyncMap;
-
-DocumentResource.Update("IS123", "ET123", "{}", null, twilioRestClient);
-SyncListItemResource.Update("IS123", "ES123", 1, "{}", null, twilioRestClient);
-SyncMapItemResource.Update("IS123", "MP123", "myKey" "{}", null, twilioRestClient);
-```
-
-
 [2017-10-13] 5.7.x to 5.8.x
 ---------------------------