Update link to upstream iwd documentation page

The old link redirects to the kernel's rather funny 404 page.

Author: grtcdr

src/config/network/iwd.md

@@ -22,7 +22,7 @@ operate `iwctl`.
 
 Configuration options and examples are described below. Consult the relevant
 manual pages and the [upstream
-documentation](https://iwd.wiki.kernel.org/networkconfigurationsettings) for
+documentation](https://archive.kernel.org/oldwiki/iwd.wiki.kernel.org/networkconfigurationsettings.html) for
 further information.
 
 ### Daemon configuration