fix note about Experimental! comment in changelog

changelog.md

@@ -9,7 +9,7 @@ If you are reading this on the website, then these changes are live here. -->
 ### Language
 - [`windows` `◫`](https://uiua.org/docs/windows) can now take negative window sizes
 - Add an *experimental* distinction for some functions/modifiers
-  - Experimental features are opt-in and must be enabled by putting an `# Experimental` comment at the top of a file
+  - Experimental features are opt-in and must be enabled by putting an `# Experimental!` comment at the top of a file
 - Add the experimental [`all` `⋔`](https://uiua.org/docs/all) modifier, which is a variadic generalization of [`both` `∩`](https://uiua.org/docs/both)
 - Add the experimental [`rectify` `⌅`](https://uiua.org/docs/rectify) function, which sets a function's inverse to itself
 - Add the experimental [`setinv`](https://uiua.org/docs/setinv) modifier, which sets the inverse of a function