Updated Protocol and compatibility (markdown)

Protocol-and-compatibility.md

@@ -8,7 +8,7 @@ At the link level, APRS uses the AX.25 protocol, as defined in AmateurPacket-Rad
 
 ![alt text](https://raw.githubusercontent.com/sh123/esp32_loraprs/master/images/ax25.png)
 
-- **Flag** — The flag field at each end of the frame is the bit sequence 0x7ethat separates each frame.
+- **Flag** — The flag field at each end of the frame is the bit sequence 0x7e that separates each frame.
 - **Destination Address** — This field can contain an APRS destination callsign or APRS data. APRS data is encoded to ensure that the field conforms to the standard AX.25 call sign format (i.e. 6 alphanumeric characters plus SSID). If the SSID is non-zero, it specifies a generic APRS digipeater path.
 - **Source Address** — This field contains the callsign and SSID of the transmitting station. In some cases, if the SSID is non-zero, the SSID may specify an APRS display Symbol Code.
 - **Digipeater Addresses** — From zero to 8 digipeater call signs may be included in this field. Note: These digipeater addresses may be overridden by a generic APRS digipeater path (specified in the Destination Address SSID)