Add warning in rescript-react installation doc

Author: ryyppy

pages/docs/react/latest/installation.mdx

@@ -6,6 +6,12 @@ canonical: "/docs/react/latest/installation"
 
 # Installation
 
+<Warn>
+
+**Important:** The `rescript-react` npm package has not been released yet. Please stay tuned for further announcements!
+
+</Warn>
+
 Add following dependency to your ReScript project (in case you don't have any project yet, check out the [installation instructions](/docs/manual/latest/installation) in the manual):
 
 ```