Update ChangeLog.md

ChangeLog.md

@@ -1,6 +1,6 @@
 # Change Log
 
-### 2020-xx-xx - 5.1.0-preview.5
+### 2020-06-23 - 5.1.0-preview.5
 Autorest Core version: 3.0.6287
 Modelerfour version: 4.15.378
 
@@ -11,6 +11,7 @@ Modelerfour version: 4.15.378
 - Fix bug when generating parameters with client default value and constant schema  #707
 - Make operation mixin signatures for multiapi default to default api version  #715
 - Fix name in setup.py to default to `package-name` if set  #721
+- Allow different custom base url host templates across API versions  #719
 
 ### 2020-07-07 - 5.1.0-preview.4
 Modelerfour version: 4.15.378