doc: fix typo in assert code example

PR-URL: #9704
Reviewed-By: Colin Ihrig <[email protected]>
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: Sakthipriyan Vairamani <[email protected]>
Reviewed-By: Luigi Pinca <[email protected]>

Author: vsemozhetbyt

doc/api/assert.md

@@ -345,7 +345,7 @@ assert.notStrictEqual(1, 2);
 // OK
 
 assert.notStrictEqual(1, 1);
-// AssertionError: 1 != 1
+// AssertionError: 1 !== 1
 
 assert.notStrictEqual(1, '1');
 // OK