Update release notes/v0.38.0.md

Co-authored-by: na-- <n@andreev.sh>

release notes/v0.38.0.md

@@ -31,7 +31,7 @@ export default function() {
 This release adds the ability to dump SSL keys while making TLS connections.
 You then can use these keys to decrypt all traffic that k6 generates. 
 
-To accomplish this, set the `SSLKEYLOGFILE` to some file path and run k6.
+To accomplish this, set the `SSLKEYLOGFILE` environment variable to some file path and run k6.
 This will populate the file with the keys.
 Then you can use Wireshark to capture the traffic, decrypt it, and use that for debugging.