doc,esm: document experimental warning removal

PR-URL: #35750
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Guy Bedford <guybedford@gmail.com>

Author: aduh95

doc/api/esm.md

@@ -12,6 +12,11 @@ changes:
   - version: v14.8.0
     pr-url: https://github.com/nodejs/node/pull/34558
     description: Unflag Top-Level Await.
+  - version:
+    - v14.0.0
+    - v13.14.0
+    pr-url: https://github.com/nodejs/node/pull/31974
+    description: Remove experimental modules warning.
   - version:
     - v13.2.0
     - v12.17.0