Merge pull request #3942 from TeoKohan/patch-1

Add clarification about Vite exported variables

Author: vejol

src/content/2/en/part2e.md

@@ -624,6 +624,8 @@ const api_key = import.meta.env.VITE_SOME_KEY
 
 Note that you will need to restart the server to apply the changes.
 
+**NB:** To prevent accidentally leaking environment variables to the client, only variables prefixed with VITE_ are exposed to Vite.
+
 This was the last exercise of this part of the course. It's time to push your code to GitHub and mark all of your finished exercises to the [exercise submission system](https://studies.cs.helsinki.fi/stats/courses/fullstackopen).
 
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