doc: add server header into the discarded list of http message.headers

PR-URL: #29962
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Trivikram Kamat <[email protected]>

Author: Huachao

doc/api/http.md

@@ -1765,7 +1765,7 @@ header name:
 * Duplicates of `age`, `authorization`, `content-length`, `content-type`,
 `etag`, `expires`, `from`, `host`, `if-modified-since`, `if-unmodified-since`,
 `last-modified`, `location`, `max-forwards`, `proxy-authorization`, `referer`,
-`retry-after`, or `user-agent` are discarded.
+`retry-after`, `server`, or `user-agent` are discarded.
 * `set-cookie` is always an array. Duplicates are added to the array.
 * For duplicate `cookie` headers, the values are joined together with '; '.
 * For all other headers, the values are joined together with ', '.