doc: fix a typo in util.isDeepStrictEqual

Backport-PR-URL: #19127
PR-URL: #18775
Reviewed-By: Weijia Wang <starkwang@126.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Roman Reiss <me@silverwind.io>

Author: Sho Miyamoto

doc/api/util.md

@@ -491,7 +491,7 @@ added: v9.0.0
 * `val2` {any}
 * Returns: {boolean}
 
-Returns `true` if there is deep strict equality between `val` and `val2`.
+Returns `true` if there is deep strict equality between `val1` and `val2`.
 Otherwise, returns `false`.
 
 See [`assert.deepStrictEqual()`][] for more information about deep strict