Create README.md

Release notes version update for V0.21.0

docs/README.md

+Release Notes 
+
+V0.21.0
+Main features
+* New Traffic search & Stream experience 
+  * Rich query language with full-text search capabilities on headers & body
+  * Distinct live-streaming vs paging/browsing modes, all with the filter applied
+
+* Display Improvements
+  Display source and destination IP address & service names for traffic item
+
+* Mizu Health
+  * Display warning when not all requested pods are up and running properly 
+  * Pod tapping status is reflected in the pod's list in the top bar
+
+* Mizue Telemetry 
+  Report platform type
+
+Notable bug fixes
+* mizu tap daemonset prints duplicate pods and errors
+* mizu: HTTP2 upgraded requests not shown
+* Mizu tappers wasn't deployed because of security issue - add informative message to user
+* mizu - shows several duplicates http entries