doc: fix dns.lookup and dnsPromises.lookup description

doc/api/dns.md

@@ -204,8 +204,9 @@ changes:
 * `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 IPv4 and IPv6 addresses
-    are both returned. **Default:** `0`.
+    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)`,
+    both IPv4 and IPv6 addresses are returned. **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
@@ -953,8 +954,11 @@ added: v10.6.0
 * `hostname` {string}
 * `options` {integer | Object}
   * `family` {integer} The record family. Must be `4`, `6`, or `0`. The value
-    `0` indicates that IPv4 and IPv6 addresses are both returned. **Default:**
-    `0`.
+    `0` indicates that either an IPv4 or IPv6 address is returned. If
+    value `0` used with `{ all: true }` (see below), both IPv4 and IPv6 addresses
+    are returned. **Default:** `0`.
+    value `0` used with `{ all: true }`, both IPv4 and IPv6 addresses
+    are returned. **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 `Promise` is resolved with all addresses in