docs: add gaming-oriented routing tutorial (#527)

Co-authored-by: Sumire (菫) <[email protected]>

docs/en/configuration/gaming-oriented-routing.md

@@ -0,0 +1,72 @@
+DAE Config  (e.g. /etc/dae/config.dae)
+
+```
+routing {            
+#stop using low efficiency socks5 proxy or else
+#dscp(8) -> game             
+
+#using fw mark for ultra fast gaming experience
+dscp(8) -> direct(mark:0x800)
+}
+
+```
+
+OpenWRT Network Config  (e.g. /etc/config/network)
+
+Please choose the tunnel MTU carefully (CS2 Require MTU > 1300 due to UDP Ping (1300 bytes))
+
+```
+config interface 'wg100'                                                 
+        option proto 'wireguard'                                         
+        option private_key '[Client Private Key]'
+        list addresses '10.7.0.2/24'                                    
+        list addresses 'fd42:42:42::2/64'                               
+        option mtu '1420'                                               
+                                                                        
+config wireguard_wg100                                                  
+        option public_key '[Server Public Key]'
+        option endpoint_host '[Your Server IP]'
+        list allowed_ips '0.0.0.0/0'  
+        list allowed_ips '::/0'       
+                                      
+config route                          
+        option interface 'wg100'      
+        option target '0.0.0.0/0'     
+        option gateway '10.7.0.1'     
+        option table '114'            
+                                      
+config route6                         
+        option interface 'wg100'      
+        option target '::/0'          
+        option gateway 'fd42:42:42::1'
+        option table '114'       
+                                 
+config rule                      
+        option lookup '114'      
+        option mark '0x800/0x800'
+                                 
+config rule6                     
+        option lookup '114'      
+        option mark '0x800/0x800'
+```
+
+OpenWRT Firewall Config (e.g. /etc/config/firewall)
+
+```
+config nat                       
+        option src 'vpn'         
+        option src_ip '[Gaming PC IPv4 Address]'
+        option target 'SNAT'         
+        option snat_ip '10.7.0.2'    
+        option family 'ipv4'         
+        list proto 'all'    
+
+config nat                     
+        option src 'vpn'
+         option src_ip '[Gaming PC IPv6 Address]'
+        option target 'SNAT'
+        option snat_ip 'fd42:42:42::2'
+        option family 'ipv6'
+        list proto 'all'
+
+```