Add release notes for v1.11.0-rc.1

WHATSNEW.md

-osTicket 1.11.0
-==================
+osTicket 1.11.0-rc.1
+====================
 ## Major New Features
+- Create Ticket or Task from Thread Entry
 - Custom Columns/Custom Queues
 - Inline Edit
 - Ticket Referral
@@ -11,6 +12,8 @@ osTicket 1.11.0
 - Nested Knowledgebase Categories
 
 ### Enhancements
+- Fix Custom Department Field (#3976)
+- Remove Future Search/Filter Criteria if Invalid
 - Dashboard Statistics
 - Fix Vimeo iFrames
 - Fix randNumber()