doc: fix crypto.hkdf callback derivedKey type

PR-URL: #39453
Reviewed-By: James M Snell <[email protected]>

Author: panva

doc/api/crypto.md

@@ -3857,7 +3857,7 @@ added: v15.0.0
   the maximum HKDF output 16320 bytes).
 * `callback` {Function}
   * `err` {Error}
-  * `derivedKey` {Buffer}
+  * `derivedKey` {ArrayBuffer}
 
 HKDF is a simple key derivation function defined in RFC 5869. The given `ikm`,
 `salt` and `info` are used with the `digest` to derive a key of `keylen` bytes.