doc: remove outdated sentence

The `'IPv4'` and `'IPv6'` values are no longer supported.

Fixes: #54961

doc/api/dns.md

@@ -246,12 +246,11 @@ changes:
 
 * `hostname` {string}
 * `options` {integer | Object}
-  * `family` {integer|string} The record family. Must be `4`, `6`, or `0`. For
-    backward compatibility reasons,`'IPv4'` and `'IPv6'` are interpreted as `4`
-    and `6` respectively. The value `0` indicates that either an IPv4 or IPv6
-    address is returned. If the value `0` is used with `{ all: true }` (see
-    below), either one of or both IPv4 and IPv6 addresses are returned,
-    depending on the system's DNS resolver. **Default:** `0`.
+  * `family` {integer} The record family. Must be `4`, `6`, or `0`. The value
+    `0` indicates that either an IPv4 or IPv6 address is returned. If the value
+    `0` is used with `{ all: true }` (see below), either one of or both IPv4 and
+    IPv6 addresses are returned, depending on the system's DNS resolver.
+    **Default:** `0`.
   * `hints` {number} One or more [supported `getaddrinfo` flags][]. Multiple
     flags may be passed by bitwise `OR`ing their values.
   * `all` {boolean} When `true`, the callback returns all resolved addresses in