First version of new CONTRIBUTING.md

[curquiza]

• Add the new CONTRIBUTING.md, highly based on the same guideline as the Meilisearch and Tokenizer ones.
• The "Development Workflow" section is WIP and should be improved but not in this PR. (I will open an issue once it's merge). However, if you see wrong information, please correct them 😇
• I also updated the README accordingly. The README is the "What is it?" and the "How to use the library? (for the users, not the contributor/maintainers)" documentation. The CONTRIBUTING is the "How to contribute/maintain the repo?" documentation, so mostly for the core team and for every contributor. I will open an issue too once this PR is merged.

[Kerollmops]

C'est validax!

[Kerollmops]

bors merge

[bors]

👎 Rejected by PR status