Add CONTRIBUTING.md

Referenced documents: 
https://mozillascience.github.io/working-open-workshop/contributing/
https://opensource.com/life/16/3/contributor-guidelines-template-and-tips
https://github.com/sr6033/lterm#contributing
https://github.com/opengovernment/opengovernment/blob/master/CONTRIBUTING.md
https://github.com/rails/rails/blob/main/CONTRIBUTING.md
https://github.com/atom/atom/blob/master/CONTRIBUTING.md

Author: penyuan

CONTRIBUTING.md

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+# Contributing
+
+Thank you for considering contributing to this project. Help in any form, big or small, is much appreciated. Programming skills are not needed.
+
+Please follow the [Contributor Covenant](https://www.contributor-covenant.org/version/2/0/code_of_conduct/) Code of Conduct 2.0 which applies to all activities within this repository.
+
+Right now, the best way to get in touch is by opening an issue in the [issue tracker](https://github.com/OPEN-NEXT/wp2.2_dev/issues). When communicating, it is better to err on the side of *providing as much detail and specifics as possible*.
+
+## Install & usage issues
+
+If you encounter *any* issues while installing or running the code in this repository, please open an issue. There is a bug report template which could be used as needed.
+
+Ideas/feature requests would be gratefully received as well, especially ones regarding **how to improve this dashboard to better serve the needs of open source hardware (or any other open source) development communities**.
+
+## Contributing code
+
+This is where basic skills in `git` and [GitHub](http://help.github.com/) are assumed. Below are general recommendations adapted from [this post](https://opensource.com/life/16/3/contributor-guidelines-template-and-tips) (CC BY-SA 4.0):
+
+1. Clone this repository to your local machine using `git clone https://github.com/OPEN-NEXT/wp2.2_dev.git`.
+2. Create a new branch for your fix using `git checkout -b [branch-name-here]` (use a short but descriptive branch name).
+3. Make the appropriate changes for the issue you are trying to address or the feature that you want to add.
+4. Use `git add [insert-paths-of-changed-files-here]` to add the file contents of the changed files to the "snapshot" `git` uses to manage the state of the project, also known as the index.
+5. Use `git commit -m "[Insert a short message of the changes made here]"` to store the contents of the index with a descriptive message. This message should be capitalised and written in imperative present tense e.g. "Fix type-hinting" instead of "Type-hinting fixed". Do not end this message with a period.
+6. Push the changes to the remote repository using `git push origin [branch-name-here]`.
+7. Submit a [GitHub pull request](http://help.github.com/pull-requests/) to this repository (pull requests are a GitHub feature).
+8. Title the pull request with a short description of the changes made and the issue or bug number associated with your change. For example, you can title an issue like so "Added more log outputting to resolve #4352".
+9. In the description of the pull request, explain the specific changes you made, any issues you think exist with the pull request you made, and any questions you have for the maintainer. It's OK if your pull request is not perfect.
+
+Thank you in advance for your contribution.