Feature : I've made a docker file to compile the rom

[wissammm]

Hello,
I’ve created a Docker setup for my reinforcement learning project on pret/pokeemerald. Would you be interested in a PR that adds Docker support to compile the ROM (modern)?

[JordonVW]

Just out of curiosity would this be to negate the Linux aspect of compiling a rom and make it a Windows application instead?

Because that is something that has put me off about producing a rom hack myself.

[P3NG00]

Also discussed here #2278