[1.x] Install script globally

[sfelix-martins]

I didn't have a good experience to up the env and access the workspace container with docker-compose exec --user=laradock workspace bash. I had to back to laradock root folder and execute the command.

I think that if install the script globally it can be execute from laradock root folder. E.g.:

cd ~/laradock
upenv my_site
docker-compose exec --user=laradock workspace bash

The Projects.yml file should be created in the laradock root folder.

WARNING A global installer will be required using brew, apt-get, etc.

An alternative is continue the same installation and usage flow and just add instructions to README.