Missing prerequisites for running ci test shield tests

[maclobdell]

Need to add to the list of Pre-requisites

• git
• mercurial
• compiler such as GCC, ARM Compiler 5, or IAR

also python modules

• mbed-ls
• pyserial

For the python modules, how about a requirements file that can ensure they are installed? Suggest to add a requirements.txt file.
And add this command to the setup instructions:
pip install -r requirements.txt

[0xc0170]

This is well know (to mbed OS) requirements. Shoudn't this be documented somewhere as part of mbed OS, and this repository just points to this documentation ?

[BlackstoneEngineering]

@maclobdell we can add this to the readme, just to be extra explicit. Out of curiosity, what is the use case that you are seeing this as a problem in?
@0xc0170 lets add a line to the readme that says it has the same requirements as mbed-os and then links to the requirements for mbed os?

[0xc0170]

@0xc0170 lets add a line to the readme that says it has the same requirements as mbed-os and then links to the requirements for mbed os?

PR sent