Adding extra requirements in instructions

I have tested MaVoixSupportGenerator by running the following command in MaVoixSupportGenerator/:

php -S localhost:7777

I managed to go all the way to get my image (Facebook profile), but you should add the following requirements:

installing PHP command line
creating tmp/ folder. It may have enough permissions by default, but if not, give it 777
having the GD module installed in PHP. In Debian Linux distributions:

sudo apt-get install phpN-gd

Where N is your version of PHP. For Ubuntu 16.04, it's 7.0:

sudo apt-get install php7.0-gd

If unsure, get your PHP version with the following command:

php -v

Just give me thumbs up and I'll prepare a PR :)

MaVoix / MaVoixSupportGenerator