Merge pull request #721 from candy-lang/contributing-guide

Add contributing guide

CONTRIBUTING.md

@@ -0,0 +1,59 @@
+# Contributing
+
+Thank you for your interest in contributing to Candy! 🎉
+
+We use [Discord](https://discord.gg/5Vr4eAJ7gU) for communication.
+If you have any questions, please don't hesitate to ask us there :)
+
+## Local Setup
+
+Follow the [README's How to use Candy section](https://github.com/candy-lang/candy#how-to-use-candy) to set up your development environment.
+
+## Selecting an issue
+
+Visit the [GitHub Project](https://github.com/orgs/candy-lang/projects/1/views/1) and look for an interesting problem you want to solve.
+
+If you're new to this project, we recommend issues tagged with [<kbd>good first issue</kbd>](https://github.com/orgs/candy-lang/projects/1/views/4).
+If there are no such issues (or too few), please write us [a message on Discord][Discord].
+
+If an issue's title or description are not clear, please don't hesitate to comment on that issue and ask for clarification.
+
+Once you have selected an issue to work on, assign yourself to that issue so we don't end up with two people doing the same thing. :)
+If you don't have permissions to do this, just comment on that issue and we'll assign you.
+
+If the issue is larger than expected and some parts of it can be fixed more easily in a self-contained manner, please open new issue(s) and link to them in the original issue.
+You can then solve these smaller issue(s) on new branches.
+
+## Working on Stuff
+
+1. Create a branch for working on your assigned issue and switch to it locally:
+   - If you have write access to the repository:
+     On the right side of the issue page, under _Development_, click _Create a branch_, then click _Create branch_.
+   - If you don't have write access to the repository:
+     1. Fork the repository.
+     2. Create a branch called `<issue ID>-issue-title-in-kebab-case`.
+        E.g., for issue [#661](https://github.com/candy-lang/candy/issues/661) “Show more hints in IRs (values of constant etc.)”, the branch name should be `661-show-more-hints-in-irs-values-of-constant-etc`.
+2. Implement your changes.
+   Please add tests and make sure that there are no linter warnings.
+3. Commit your changes.
+   - You can also create smaller commits while you're working on your changes.
+   - Commit messages should be in imperative mood and start with a capital letter, e.g., “Add contributing guide”
+4. Push your changes to GitHub.
+5. When you're done, file a pull request (PR).
+   - Please give it a meaningful title and enter the corresponding issue number in the description.
+   - On the right side, please select the corresponding type label(s) (called <kbd>T: …</kbd>, e.g., <kbd>T: Feature</kbd>).
+   - Optionally, on the right side select reviewer(s).
+   - The remaining fields will be filled out automatically.
+
+We will take a look at your code, and, once all checks pass, your code can get merged 🏖️
+
+## Pull Request Conversations
+
+Regarding conversations (comments from code review) on pull requests:
+
+- If you write a reply, _don't_ mark the conversation as resolved.
+  Otherwise, the other person won't see your reply.
+- If you are sure that you fully addressed a comment, _do_ mark the conversation as resolved.
+  _Don't_ reply “Done” or something similar.
+
+[Discord]: https://discord.gg/5Vr4eAJ7gU