Updated Frequently asked questions (markdown)

Frequently-asked-questions.md

@@ -15,4 +15,11 @@
 - Application keeps reconnecting to USB modem
   - Make sure Serial debugging is disabled in modem and serial USB is used only for data transfer
   - Make sure it works with empty sketch, where serial is initialized, but no data and logging transfers performed
-  - Make sure modem serial boot log is disabled on platforms such as ESP32
+  - Make sure modem serial boot log is disabled on platforms such as ESP32
+- APRS-IS only tracking
+  - Select loopback TNC mdoem
+  - Enable APRS from setttings
+  - Enable APRS-IS from settings
+  - Fill callsign, SSID, select APRS symbol
+  - Go to Internet APRS and fill in APRS-IS passcode
+  - Enable own APRS to APRS-IS