Add instructions for joining wifi

Author: gminn

README.md

@@ -48,3 +48,16 @@ upload-mcu-symbols .pio/build/espidf/firmware.elf
 ```bash
 pio run --target upload --target monitor
 ```
+
+4. Join a wifi network
+
+```bash
+esp32> join <ssid> <password>
+```
+
+5. Save wifi settings to NVM so it connects automatically on boot
+
+```bash
+esp32> settings_set "wifi_ssid" "your network name"
+esp32> settings_set "wifi_password" "your-wifi-password"
+```