docs: use a 5GHz channel for the RPI access point

Author: AlyaGomaa

docs/installation.md

@@ -336,9 +336,13 @@ Meaning it wil kick out the malicious device from the AP.
 1. Connect your RPI to your router using an ethernet cable
 2. Run your RPI as an access point using [create_ap](https://github.com/oblique/create_ap)
 
-`sudo create_ap wlan0 eth0 rpi_wifi mysecurepassword`
+`sudo create_ap wlan0 eth0 rpi_wifi mysecurepassword -c 40`
 
-where `wlan0` is the wifi interface of your RPI and `eth0` is the ethernet interface.
+where `wlan0` is the wifi interface of your RPI, `eth0` is the ethernet interface and `-c 40` is the channel of the access point.
+
+We chose channel 40 because it is a 5GHz channel, which is faster and less crowded than the 2.4GHz channels.
+
+Note: Please make sure your RPI model supports 5GHz channels. If not, you can use `-c 1` for 2.4GHz.
 
 3. Run Slips in the RPI using the command below to listen to the traffic from the access point.