Add frame-src to Piwik plugin as * may be overwritten

Change-Id: I39023b8d662c0130e216d419d83aa076f4b7aa02
diff --git a/Changes b/Changes
index 86f0be8..bfe102f 100755
--- a/Changes
+++ b/Changes
@@ -32,6 +32,8 @@
           to simplify asset configuration in proxy servers.
         - Fix working directory for plugin configuration.
         - Make mailto: embedding CSP compliant.
+        - Add frame-src to Piwik plugin as '*' may be
+          overwritten.
 
 0.40 2020-12-17
         - Modernize ES and fix in-loops.