doc: use serial comma in dns docs

Refs: nodejs/node#11321
Refs: nodejs/node#17384

PR-URL: nodejs/node#43145
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Mohammed Keyvanzadeh <mohammadkeyvanzade94@gmail.com>

doc/api/dns.md

@@ -1323,7 +1323,7 @@ using `dns.resolve()` and using the address instead of a host name. Also, some
 networking APIs (such as [`socket.connect()`][] and [`dgram.createSocket()`][])
 allow the default resolver, `dns.lookup()`, to be replaced.
 
-### `dns.resolve()`, `dns.resolve*()` and `dns.reverse()`
+### `dns.resolve()`, `dns.resolve*()`, and `dns.reverse()`
 
 These functions are implemented quite differently than [`dns.lookup()`][]. They
 do not use getaddrinfo(3) and they _always_ perform a DNS query on the