Better makefile, plotting, saving the data, and cleanup

Makefile

@@ -1,6 +1,17 @@
+help:
+	# plot - Plot the latest measurement
+	# monitor - Build and monitor onto esp if connected to /dev/ttyUSB0
+	# env - Start the esp environment on nix
+	# server - Start the go server
+	
 monitor:
 	idf.py -p /dev/ttyUSB0 flash monitor
+
 env:
 	nix --experimental-features 'nix-command flakes' develop github:mirrexagon/nixpkgs-esp-dev#esp32-idf
+
+plot:
+	nix-shell --pure --run "python plot.py"
+
 server:
 	go run main.go