Adding of docker installation in CONTRIBUTING.md

[qcoudeyr]

Description

Adding of docker installation in contributing.md.
As I have an infrastructure using docker, I wanted a Dockerized environment for the streaks stats.
So, I have created a Dockerfile and a docker compose example on my repo.
I will implement it in my docker compose so it will be accessible using a reverse proxy.
I have updated the contribution.md to add this method accessible to people wanting to self-host their own version without the pain of dealing with dependencies.

Type of change

• Updated documentation (updated the readme, templates, or other repo files)

How Has This Been Tested?

• Tested locally with a valid username
• Tested locally with an invalid username

Checklist:

• I have checked to make sure no other pull requests are open for this issue
• The code is properly formatted and is consistent with the existing code style
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings

Screenshots

No visual change have been made.