examples: add minimal README to at-cmd

Signed-off-by: deadprogram <ron@hybridgroup.com>

examples/lora/atcmd/README.md

@@ -0,0 +1,29 @@
+# AT-CMD implementation of at-lora command set
+
+```
+$ tinygo monitor
+Connected to /dev/ttyACM0. Press Ctrl-C to exit.
++AT: OK
++VER: 0.0.1 sx127x v18
+```
+
+# Building
+
+## Simulator
+
+```
+tinygo flash -target pico ./examples/lora/atcmd/
+```
+
+## PyBadge with LoRa Featherwing 
+
+```
+tinygo flash -target pybadge -tags featherwing ./examples/lora/atcmd/
+```
+
+## LoRa-E5 
+
+```
+tinygo flash -target lorae5 ./examples/lora/atcmd/
+```
+