Updated Protocol and compatibility (markdown)

Protocol-and-compatibility.md

@@ -5,7 +5,7 @@
 - **Server iGate** by default supports only classical `AX25` frames over LoRa (as defined in http://www.aprs.org/doc/APRS101.PDF page 12, see section below). It should enable interoperability with classical Linux APRS software, such as Xastir with `kissattach`. 
   - NB! Some popular LoRa ARPS implementations transfer plain text APRS messages over LoRa, for this mode operations need to set `cfg.EnableTextPackets/CFG_TEXT_PACKETS` to `true`, in this case iGate will transmit, receive and digirepeat text based APRS messages instead of classical AX25 frames.
 
-# APRS AX.25 protocol
+# APRS AX.25 binary protocol
 At the link level, APRS uses the AX.25 protocol, as defined in AmateurPacket-Radio Link-Layer Protocol, utilizing Unnumbered Information (UI) frames exclusively. This means that APRS runs in connection less mode, whereby AX.25 frames are transmitted without expecting any response, and reception at the other end is not guaranteed.At a higher level, APRS supports a messaging protocol that allows users tos end short messages (one line of text) to nominated stations, and expects to receive acknowledgements from those stations.
 
 ![alt text](https://raw.githubusercontent.com/sh123/esp32_loraprs/master/images/ax25.png)
@@ -19,5 +19,5 @@ At the link level, APRS uses the AX.25 protocol, as defined in AmateurPacket-Rad
 - Information Field — This field contains more APRS data. The first character of this field is the APRS Data Type Identifier that specifies the nature of the data that follows.
 - Frame Check Sequence — The FCS is a sequence of 16 bits used for checking the integrity of a received frame.
 
-# TNC2 protocol
+# TNC2 text protocol
 TNC2 protocol does not use KISS, it sends text based APRS messages, multiple messages are separated by using new line character `\n`.