Updated Troubleshooting Guide (markdown)

Troubleshooting-Guide.md

@@ -7,6 +7,7 @@ This page sums up the most frequently encountered issues for different wireless
 | Erratic behavior, instability | any | [Hardware issues](https://github.com/jgromes/RadioLib/wiki/Troubleshooting-Guide#hardware-issues) |
 | Reset on transmit | N/A | [Insufficient power supply](https://github.com/jgromes/RadioLib/wiki/Troubleshooting-Guide#insufficient-power-supply) |
 | Unable to initialize | -2 or -16 | [Incorrect SPI interface](https://github.com/jgromes/RadioLib/wiki/Troubleshooting-Guide#incorrect-spi-interface), bad pinout |
+| Receiver timeout | -6 | [Blocking receive mode](https://github.com/jgromes/RadioLib/wiki/Troubleshooting-Guide#receiver-timeout) |
 
 ## Hardware issues
 
@@ -27,3 +28,9 @@ Use a dedicated, properly filtered linear (not switched!) regulator to power the
 ### Incorrect SPI interface
 
 Some platforms support multiple SPI interfaces. If you do not use the correct one, RadioLib will not be able to initialize the module (typically ending in a -2 or -16 error code). See [this wiki page](https://github.com/jgromes/RadioLib/wiki/Basics#non-standard-spi-setup) for details on how to select the correct SPI interface.
+
+## Usage issues
+
+### Receiver timeout
+
+The `receive` method is a blocking method - this means that it will block executuion until an event occurs. In case of RadioLib, this is either packet being received, or a timeout. IF the method finishes with a timeout, it will report a -6 error code. However, this can be expected if there were no packets received during the receive window.