diff --git a/pkg/sdk3rd/matrix/client.go b/pkg/sdk3rd/matrix/client.go
index 3a47d9d8..378ad0d8 100644
--- a/pkg/sdk3rd/matrix/client.go
+++ b/pkg/sdk3rd/matrix/client.go
@@ -1,3 +1,5 @@
+// A simple SDK client for Matrix (ElementX).
+// API documentation: https://spec.matrix.org/latest/client-server-api/
 package matrix
 
 import (