P2P: Add forgotten allow_cross_connection example

hostapd/hostapd.conf

@@ -990,6 +990,9 @@ own_ip_addr=127.0.0.1
 # Enable P2P Device management
 #manage_p2p=1
 
+# Allow cross connection
+#allow_cross_connection=1
+
 ##### Multiple BSSID support ##################################################
 #
 # Above configuration is using the default interface (wlan#, or multi-SSID VLAN