update changelog for 1.15.0 release (#49)

diff --git a/core/ruby2.5Action/CHANGELOG.md b/core/ruby2.5Action/CHANGELOG.md
index 5f0c15c..8eb3ac5 100644
--- a/core/ruby2.5Action/CHANGELOG.md
+++ b/core/ruby2.5Action/CHANGELOG.md
@@ -19,6 +19,9 @@
 
 # Ruby 2.5 OpenWhisk Runtime Container
 
+## 1.15.0
+  - Build proxy using golang 1.15 and openwhisk-runtime-go 1.16.0 (#48)
+
 ## 1.14.0
   - Support for __OW_ACTION_VERSION (openwhisk/4761)
 
diff --git a/core/ruby2.6ActionLoop/CHANGELOG.txt b/core/ruby2.6ActionLoop/CHANGELOG.txt
index 1a769d0..7219f9e 100644
--- a/core/ruby2.6ActionLoop/CHANGELOG.txt
+++ b/core/ruby2.6ActionLoop/CHANGELOG.txt
@@ -19,5 +19,8 @@
 
 # Ruby 2.6 OpenWhisk Runtime Container
 
+## 1.15.0
+  - Build proxy using golang 1.15 and openwhisk-runtime-go 1.16.0 (#48)
+
 ## 1.14.0
   - Initial Release