doc: fix myUrl is not defined in url

Fixes a typo in the variable name in the URL code example in doc.
Renames `myUrl` to `myURL` for consistency and readability.

PR-URL: #46968
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Harshitha K P <harshitha014@gmail.com>
Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com>
Reviewed-By: Akhil Marsonya <akhil.marsonya27@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Deokjin Kim <deokjin81.kim@gmail.com>

doc/api/url.md

@@ -554,14 +554,14 @@ instance, the `URL` object will not percent encode the ASCII tilde (`~`)
 character, while `URLSearchParams` will always encode it:
 
 ```js
-const myUrl = new URL('https://example.org/abc?foo=~bar');
+const myURL = new URL('https://example.org/abc?foo=~bar');
 
-console.log(myUrl.search);  // prints ?foo=~bar
+console.log(myURL.search);  // prints ?foo=~bar
 
 // Modify the URL via searchParams...
-myUrl.searchParams.sort();
+myURL.searchParams.sort();
 
-console.log(myUrl.search);  // prints ?foo=%7Ebar
+console.log(myURL.search);  // prints ?foo=%7Ebar
 ```
 
 #### `url.username`
@@ -1271,7 +1271,7 @@ console.log(urlToHttpOptions(myURL));
 const { urlToHttpOptions } = require('node:url');
 const myURL = new URL('https://a:b@測試?abc#foo');
 
-console.log(urlToHttpOptions(myUrl));
+console.log(urlToHttpOptions(myURL));
 /*
 {
   protocol: 'https:',