Updated Getting Started (markdown)

Getting-Started.md

@@ -56,10 +56,21 @@ To install these packages, use the following command:
 
 > sudo apt-get install build-essential libreadline-dev libffi-dev git pkg-config
 
-Then, clone the repository to your local machine, or if you have created a virtual environment [see above](https://github.com/micropython/micropython/wiki/Getting-Started## Creating-A-Virtual-Environment):
+Then, clone the repository to your local machine, or if you have created a [virtual environment](https://github.com/micropython/micropython/wiki/Getting-Started##Creating-A-Virtual-Environment) clone into your **project** folder.
 
 > git clone --recurse-submodules https://github.com/micropython/micropython.git
 
+First check that the mpy-cross script exists to allow cross compiling. This may be fixed at some point in the future to be done automatically but for now you need to do this manually. 
+Change directory to the mpy-cross directory here:
+
+> cd ~/virtalenv/microPython/project/micropython/mpy-cross
+
+If mpy-cross does not exist do:
+
+> make
+
+You should notice the mpy-cross executable is now created.
+
 Change directory to the Unix build directory:
 
 > cd ./micropython/ports/unix