feat: Init Contribution and fill Readme

CONTRIBUTION.md

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+# 📒 Contribution guidelines
+Contributions and discussions are welcomed to this project!
+
+## Code of conduct
+
+I believe that healthy debate and disagreement are essential to a healthy project and community. However, it is never ok to be disrespectful. Diverse opinions are welcomed as long as respect is maintained.
+
+- Be friendly and welcoming.
+- Be patient.
+- Be thoughtful.
+- Be respectful.
+- Be charitable.
+- Be constructive.
+- Be responsible.
+
+## TOC
+
+Learn about:  
+1. [Open a topic to discuss](#-discussions)  
+2. [Open an issue about a bug, improvement or to suggest icons](#️-i-would-like-to-report-a-bug-or-an-issue)  
+3. [Open a PR to patch or contribute to the project]()  
+
+## 💬 Discussions
+
+> Discussion are topics users can speak about, but doesn't relate to a problem or an actionnable task. Discussion must be related to the project.
+
+To open a topic, go to the discussion tab on this project.
+
+## 🐞 Issues
+
+> Issues allow users to report bugs, request improvement or suggest ideas.
+
+You can open an issue for the following categories. Use the corresponding labels.
+* **minor bug**: Bug that slightly affect visual or render aspects of an icon, or that is not impeding the project. 
+* **major bug**: Annoyance on the project or icons not following the original style.
+* **critical bug**: Icon that is visually different from original, or bug blocking the project. 
+* **idea**: Ideas to think on before becoming something else.
+* **enhance an icon**: Design changes that improve visuals or optimise code.
+* **design an icon**: Task that consist of designing an Icon or a set of Icon.
+
+Specific rules applies, and not following them may result in the closing of the issue.
+* Issue must have a label from one of the available categories
+* Issue must be sufficiently described, clear and not misleading.
+* Issue may be flagged as _duplicate_ if the topic is already discussed on another issue. To avoid your issue being closed early, please search for duplicated before opening one and comment or upvote it instead.
+
+## 🪄 Code contribution
+
+> Code contribution can take form of new icons in SVG or changes to existing icons in the goal to improve them.
+
+Pull Requests must follow the rules below:
+- Contributions must be related to an issue. Please create one before opening a PR.
+- Code related to icons must follow icons design guidelines
+
+## Icon design guideline
+
+- Icons must be in the **style and spirit of the original work** from Marc.
+- Icons must be in **SVG**.
+- Icons must be designed to be **legible in any size from 16×16px to 64×64px**. It must have the right balance between too much details and too little.
+- Icon improvement based on existing icons must be as close as possible to the original design.
+- Icon must render without visual artefact in today's broswer such as WebKit, Blink, Gecko.
+