Create a 'how to create an environment' documentation

[FelipeMartins96]

There is an environment example at the readme: https://github.com/robocin/rSoccer#example-code---environment
However this example lacks documentation and has some errors, a simple guide explaining how to create an environment would improve the repo!

[Khushi-agarwal]

@FelipeMartins96 can I work on this issue?

[goncamateus]

@Khushi-agarwal Sure! Be welcomed to our repo!