diff --git a/changelog.d/3645.misc b/changelog.d/3645.misc
new file mode 100644
index 0000000000000000000000000000000000000000..0fe6b28da1733129fffa53a9e69d649558c8af77
--- /dev/null
+++ b/changelog.d/3645.misc
@@ -0,0 +1 @@
+Update CONTRIBUTING to mention newsfragments.