Add cross compiling instruction

README.md

@@ -1,3 +1,17 @@
 # HelloWorld
 
-Experimental project to test end to end development process : continuous integration, monitoring, cross-compilation, distributing, etc.
+Experimental project to test end to end development process : continuous integration, monitoring, cross-compilation, distributing, etc.
+
+## Cross compilation
+
+### GNU/Linux
+
+It is assumed that your are currently using a GNU/Linux distribution, so the default `linux-compiler` is `g++` found in the environment.
+
+### Windows
+
+You need the cross-compiler `i686-w64-mingw32-g++-win32`, you can install it in Debian :
+
+```sh
+sudo apt install g++-mingw-w64-i686
+```