Updated docs

docs/Building.md

@@ -8,6 +8,12 @@ From the Arduino library manager:
 
 # Automated build from the command line
 
-    bash install.sh
+    make upload
 
-This will install [arduino-cli](https://github.com/arduino/arduino-cli) if not already installed, download the esp8266 board as well as all required libraries, build TTyGO and upload it to your board (by default via /dev/ttyUSB0, set TTGOTERM to the device to override).
+This will install
+[arduino-cli](https://github.com/arduino/arduino-cli) if not already
+installed, download the esp8266 board as well as all required
+libraries, build TTyGO and upload it to your board. To use a
+non-standard serial port run e.g.
+
+    make TTGOTERM=/dev/ttyUSB5 upload