Update RELEASE_NOTES.md

Author: Danthar

RELEASE_NOTES.md

@@ -1,6 +1,6 @@
 #### 1.4.8 June 23 2020 ####
 
-* Updated to Akka.NET v1.4.8
+* Updated to [Akka.NET v1.4.8](https://github.com/akkadotnet/akka.net/releases/tag/1.4.8)
 * Support for exceptions logging in non-error log levels [#109](https://github.com/akkadotnet/Akka.Logger.Serilog/pull/109)
 
 #### 1.4.3 March 27 2020 ####