README: Update with details about ESP8266

Author: raimue

README.md

@@ -1,12 +1,31 @@
-Experiments with Arduino
-========================
+# Experiments with Arduino
 
-This repository contains all sorts of stuff related to Arduino. This is mostly just my own stuff as I use it and is not necessarily meant for direct use by others. Documentation might be missing, but feel free to ask if you find anything interesting you would like to know more about.
+This repository contains all sorts of stuff related to Arduino. This is mostly
+just my own stuff as I use it and is not necessarily meant for direct use by
+others. Documentation might be missing, but feel free to ask if you find
+anything interesting you would like to know more about.
 
-git submodule configuration
----------------------------
+## git submodule configuration
 
 This repository uses external repositories using git submodules:
 
     $ git submodule init
     $ git submodule update
+
+
+## Boards Management
+
+### AVR
+
+Everything is builtin into Arduino and Arduino-Makefile. No special
+configuration necessary.
+
+
+### ESP8266
+
+Support for esp8266 can be enabled by downloading additional tools. Refer to
+the official [ESP8266 Arduino Core](https://arduino-esp8266.readthedocs.io/)
+instructions.
+
+Additonallity, [arduino-cli](https://github.com/arduino/arduino-cli) is
+required for compilation and for flashing the device.