Add Contributing file

CONTRIBUTING.md

@@ -0,0 +1,42 @@
+# Contributing to Turbo Cache
+
+Turbo Cache welcomes contribution from everyone. Here are the guidelines if you are
+thinking of helping us:
+
+
+## Contributions
+
+Contributions to Turbo Cache or its dependencies should be made in the form of
+GitHub pull requests. Each pull request will be reviewed by a core contributor
+(someone with permission to land patches) and either landed in the main tree or
+given feedback for changes that would be required. All contributions should
+follow this format, even those from core contributors.
+
+Should you wish to work on an issue, please claim it first by commenting on
+the GitHub issue that you want to work on it. This is to prevent duplicated
+efforts from contributors on the same issue.
+
+## Pull Request Checklist
+
+- Branch from the main branch and, if needed, rebase to the current main
+  branch before submitting your pull request. If it doesn't merge cleanly with
+  main you may be asked to rebase your changes.
+
+- Commits should be as small as possible, while ensuring that each commit is
+  correct independently (i.e., each commit should compile and pass tests). 
+
+- Commits should be accompanied by a Developer Certificate of Origin
+  (http://developercertificate.org) sign-off, which indicates that you (and
+  your employer if applicable) agree to be bound by the terms of the
+  [project license](LICENSE). In git, this is the `-s` option to `git commit`.
+
+- If your patch is not getting reviewed or you need a specific person to review
+  it, you can @-reply a reviewer asking for a review in the pull request or a
+  comment.
+
+- Add tests relevant to the fixed bug or new feature.
+
+## Conduct
+
+Turbo Cache Code of Conduct is available in the
+[CODE_OF_CONDUCT](CODE_OF_CONDUCT.md) file.