docs: add mdn link to web-request-filter.md (#36617)

* Add MDN link to web-request-filter.md

When I was using the Electron docs I wanted to know how to use [webRequest.onBeforeSendHeaders](https://www.electronjs.org/docs/latest/api/web-request#webrequestonbeforesendheadersfilter-listener) but I was unable to correctly guess the correct format for the `WebRequestFilter` URL strings, and there was no explanation in the Electron docs. Eventually I googled it and found the MDN article which helped me.

Co-authored-by: Hugh Davey <[email protected]>

* Update docs/api/structures/web-request-filter.md

Co-authored-by: Black-Hole <[email protected]>

Co-authored-by: Hugh Davey <[email protected]>

* Update docs/api/structures/web-request-filter.md

Co-authored-by: Black-Hole <[email protected]>

Co-authored-by: Hugh Davey <[email protected]>

Co-authored-by: trop[bot] <37223003+trop[bot]@users.noreply.github.com>
Co-authored-by: Hugh Davey <[email protected]>

docs/api/structures/web-request-filter.md

@@ -1,3 +1,3 @@
 # WebRequestFilter Object
 
-* `urls` string[] - Array of URL patterns that will be used to filter out the requests that do not match the URL patterns.
+* `urls` string[] - Array of [URL patterns](https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/Match_patterns) that will be used to filter out the requests that do not match the URL patterns.