Add contributing guide.

MANIFEST

@@ -20,6 +20,7 @@ docker/fedora/rawhide/Dockerfile
 docker/ubuntu/devel/Dockerfile
 docker/ubuntu/latest/Dockerfile
 docker/ubuntu/rolling/Dockerfile
+docs/CONTRIBUTING.md
 docs/CONTRIBUTORS
 docs/HISTORY
 docs/LICENSE

docs/CONTRIBUTING.md

@@ -0,0 +1,75 @@
+# Contributing to Sudo
+
+Thank you for your interest in contributing to Sudo!  There are a
+number of way you can help make Sudo better.
+
+## Getting started
+
+To get an overview of Sudo, please read the [README](README).  There
+are multiple ways to contribute, some of which don't require writing
+a single line of code.
+
+## Filing bug reports/issues
+
+If you find a bug in Sudo, you may open a [GitHub issue]
+(https://github.com/sudo-project/sudo/issues) or file a [Bugzilla bug]
+(https://bugzilla.sudo.ws).  If you would rather use email, messages
+may be sent to the [sudo-workers@sudo.ws mailing list]
+(https://www.sudo.ws/mailman/listinfo/sudo-workers) \(public\) or to
+[sudo@sudo.ws] \(private\).
+
+For information on reporting security issues, please see the [SECURITY]
+(docs/SECURITY.md) file.
+
+Please include the version of sudo you are using, the operating
+system and/or distro that is affected, and step-by-step instructions
+to reproduce the problem.
+
+## Making changes to Sudo
+
+If you are interested in making changes to Sudo there are two main
+work flows:
+
+ * clone the [sudo repo](https://github.com/sudo-project/sudo), make
+   your changes, and submit a Pull Request (PR).
+   
+ * send a diff with your changes to the [sudo-workers@sudo.ws mailing list]
+   (https://www.sudo.ws/mailman/listinfo/sudo-workers) to start a discussion.
+
+In addition to the [GitHub repo](https://github.com/sudo-project/sudo),
+there is also a [mercurial repo](https://www.sudo.ws/repos/sudo).
+
+## sudo-workers mailing list
+
+If you would like to discuss your changes before submitting a PR,
+you may do so on the [sudo-workers@sudo.ws mailing list]
+(https://www.sudo.ws/mailman/listinfo/sudo-workers).
+Otherwise, discussion can simply occur as part of the PR work flow.
+
+## Fuzzing
+
+Sudo uses the [oss-fuzz project](https://github.com/google/oss-fuzz.git)
+to perform fuzzing.  Each commit to the _main_ branch will trigger
+a short fuzzing run via the [CIFuzz action]
+(https://github.com/sudo-project/sudo/actions/workflows/main.yml).
+The history of that action shows successful and failed fuzzing runs.
+
+Longer fuzzing runs occur using the ClusterFuzz infrastructure.  These
+fuzzing runs are longer than those used by CIFuzz.  A [public list of
+failures](https://bugs.chromium.org/p/oss-fuzz/issues/list?q=sudoers)
+is available.
+
+For more information on fuzzing sudo, see the [fuzzing blog post]
+(https://blog.sudo.ws/posts/2021/03/fuzz-testing-sudo/).
+
+## Translations
+
+The Free Translation Project provides translations for Sudo.  If
+you would like to contribute to Sudo's translations, please see the
+ABOUT-NLS file in the Sudo source tree or visit [the Free Translation
+Project's homepage](http://translationproject.org).
+
+There are currently two translation domains: [one for the sudo
+front-end](https://translationproject.org/domain/sudo.html) and a
+[separate one for the sudoers module and related
+utilities](https://translationproject.org/domain/sudoers.html).