doc: remove leftover WHATWG url.format section

The backport in nodejs#13054 contained a
leftover section from the WHATWG url.format, in addition to the existing
url.format. This removes this section.

doc/api/url.md

@@ -198,47 +198,6 @@ The formatting process operates as follows:
   string, an [`Error`][] is thrown.
 * `result` is returned.
 
-## url.format(URL[, options])
-
-> Stability: 1 - Experimental
-
-* `URL` {URL} A [WHATWG URL][] object
-* `options` {Object}
-  * `auth` {boolean} `true` if the serialized URL string should include the
-    username and password, `false` otherwise. Defaults to `true`.
-  * `fragment` {boolean} `true` if the serialized URL string should include the
-    fragment, `false` otherwise. Defaults to `true`.
-  * `search` {boolean} `true` if the serialized URL string should include the
-    search query, `false` otherwise. Defaults to `true`.
-  * `unicode` {boolean} `true` if Unicode characters appearing in the host
-    component of the URL string should be encoded directly as opposed to being
-    Punycode encoded. Defaults to `false`.
-
-Returns a customizable serialization of a URL String representation of a
-[WHATWG URL][] object.
-
-The URL object has both a `toString()` method and `href` property that return
-string serializations of the URL. These are not, however, customizable in
-any way. The `url.format(URL[, options])` method allows for basic customization
-of the output.
-
-For example:
-
-```js
-const myURL = new URL('https://a:b@你好你好?abc#foo');
-
-console.log(myURL.href);
-  // Prints https://a:b@xn--6qqa088eba/?abc#foo
-
-console.log(myURL.toString());
-  // Prints https://a:b@xn--6qqa088eba/?abc#foo
-
-console.log(url.format(myURL, {fragment: false, unicode: true, auth: false}));
-  // Prints 'https://你好你好?abc'
-```
-
-*Note*: This variation of the `url.format()` method is currently considered to
-be experimental.
 
 ## url.parse(urlString[, parseQueryString[, slashesDenoteHost]])
 <!-- YAML