docs: networking: packet_mmap: replace dead links with archive.org links

The original link returns 404 now. This commit replaces the dead google
site link with archive.org link.

Signed-off-by: Levi Zim <[e-mail]>
Reviewed-by: Willem de Bruijn <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

Documentation/networking/packet_mmap.rst

···
 
 Howto can be found at:
 
-    https://sites.google.com/site/packetmmap/
+    https://web.archive.org/web/20220404160947/https://sites.google.com/site/packetmmap/
 
 Please send your comments to
     - Ulisses Alonso Camaró <[e-mail]>
···
     /* bind socket to eth0 */
     bind(this->socket, (struct sockaddr *)&my_addr, sizeof(struct sockaddr_ll));
 
- A complete tutorial is available at: https://sites.google.com/site/packetmmap/
+ A complete tutorial is available at:
+ https://web.archive.org/web/20220404160947/https://sites.google.com/site/packetmmap/
 
 By default, the user should put data at::