Update README instructions

README.md

@@ -4,5 +4,23 @@
 ## Flash instructions
 
 1. Install Anet board definition for Arduino IDE from `./anet-board` ([Source](https://github.com/SkyNet3D/anet-board))
-2. Install LiquidCrystal library for Arduino using the IDE library manager
-3. Flash selecting `Anet V1.0 (Optiboot)` as board
+
+## Arduino IDE
+
+2. Flash selecting `Anet V1.0 (Optiboot)` as board
+
+## Arduino CLI
+
+2. From the root of the repository, compile with
+
+```sh
+arduino-cli compile --fqbn anet:avr:aneto Marlin
+```
+
+3. Flash using
+
+```sh
+arduino-cli upload -p /dev/ttyUSB0 --fqbn anet:avr:aneto Marlin
+```
+
+(Replace `/dev/ttyUSB0` with corresponding device)