doc: document Wi-Fi auto-shutdown workaround for TMOHS1 and CT2MHS01 (#951)

Both devices ship with a Wi-Fi Standby timer that turns off the AP
after ~10 minutes with no clients, blocking remote access to Rayhunter
until a power cycle. Previous attempt (this PR's earlier commits) added
a Rayhunter config toggle to flip gWlanAutoShutdown in WCNSS_qcom_cfg.ini,
but the same setting is already exposed in each device's native admin UI
under Settings -> Sleep -> Wi-Fi Standby, so a code change is not needed.

Replace the config toggle with:
- Device-page walkthroughs with screenshots of each native UI setting
- FAQ entry for "can't reach the web UI after leaving it alone"
- Post-install hint from the tmobile/wingtech installers pointing at
  the docs and the setting location

installer/src/tmobile.rs

@@ -94,5 +94,11 @@ async fn run_install(admin_ip: String, admin_password: String) -> Result<()> {
 
     reboot_device(addr, "reboot", &admin_ip).await;
 
+    println!();
+    println!("Note: by default the TMOHS1 shuts off Wi-Fi after 10 minutes with no clients,");
+    println!("which blocks remote access to Rayhunter until you power cycle. To keep");
+    println!("Wi-Fi always on, open http://{admin_ip}/ -> Settings -> Sleep and set");
+    println!("Wi-Fi Standby to \"Always on\". See doc/tmobile-tmohs1.md for steps.");
+
     Ok(())
 }

installer/src/wingtech.rs

@@ -144,6 +144,12 @@ async fn wingtech_run_install(admin_ip: String, admin_password: String) -> Resul
 
     reboot_device(addr, "shutdown -r -t 1 now", &admin_ip).await;
 
+    println!();
+    println!("Note: by default the CT2MHS01 shuts off Wi-Fi after ~10 minutes with no clients,");
+    println!("which blocks remote access to Rayhunter until you power cycle. To keep");
+    println!("Wi-Fi always on, open http://{admin_ip}/ -> Settings -> Sleep and set");
+    println!("Wi-Fi Standby to \"Always on\". See doc/wingtech-ct2mhs01.md for steps.");
+
     Ok(())
 }