diff --git a/docs/rules/jsx-filename-extension.md b/docs/rules/jsx-filename-extension.md
index 4f9278ff40..272addb0a1 100644
--- a/docs/rules/jsx-filename-extension.md
+++ b/docs/rules/jsx-filename-extension.md
@@ -20,6 +20,8 @@ function MyComponent() {
 }
 ```
 
+Beware this rule **only** reports JSX syntax, **not** other non-standard syntax such as experimental features or type annotations.
+
 ## Rule Options
 
 ### `allow` (default: `"always"`)