[Docs] Add CONTRIBUTING.md to solicit contributions

-Add info on ways to contribute
-Add details on how to set up dev environment
-Add info on how to submits PRs
-Include a table of contents with links to document headings

Fixes #845

CONTRIBUTING.md

@@ -0,0 +1,120 @@
+
+# Contributing to ``eslint-plugin-jsx-a11y``
+
+Thank you for your interest in becoming a part of the ongoing development of ``eslint-plugin-jsx-a11y``. 
+
+This guide covers our practices and recommendations for contributing to the project.
+
+
+## Table of Contents
+
+[Ways to contribute](#ways-to-contribute)
+
+[Dev Environment](#dev-environment)
+
+[Pull requests](#pull-requests)
+
+[Commit messages](#commit-messages)
+
+
+## Ways to contribute
+
+There are various ways to get involved. Here are a few suggestions of things we'd love some help with.
+
+#### Resolving existing issues
+
+ You can consider helping out with [issues](https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/issues?q=is%3Aissue+is%3Aopen+label%3A%22help+wanted%22) already requiring attention.
+
+#### Reporting issues
+
+If you run into problems while using `eslint-plugin-jsx-a11y`, you can report them by opening a new issue and providing as much context as you can about what you're running into, along with a failing test or code sample to help others verify and fix the issue.
+
+> **Note:** Before filing an issue, please check both open and closed issues to see if the problem has already been reported.
+
+#### Documentation
+
+We are happy to welcome contributions from anyone willing to improve documentation by adding missing information or making it more consistent and coherent.
+
+
+## Dev Environment
+
+* Install [Node.js](https://nodejs.org/en/), preferably with [nvm](https://github.com/nvm-sh/nvm)
+
+* [Fork the repo and clone your fork](https://docs.github.com/en/get-started/quickstart/fork-a-repo)
+
+* Get all dependencies
+  ```
+  npm install
+  ```
+* Add the upstream source for being able to sync main project changes back into your fork
+  ```
+  git remote add upstream git@github.com:jsx-eslint/eslint-plugin-jsx-a11y.git
+  ```
+* Run the tests and the build
+  ```
+  npm test
+  ```
+* Make and submit changes to the project source files following our [pull request submission workflow](#pull-requests)
+
+
+## Pull requests
+
+Create a new branch
+
+```
+git checkout -b issue1234
+```
+
+Commit the changes to your branch, including a coherent commit message that follows our [standards](#commit-messages)
+
+```
+git commit -a
+```
+
+Before sending the pull request, make sure your code is running on the latest available code by rebasing onto the upstream source
+
+```
+git fetch upstream
+git rebase upstream/main
+```
+
+Verify your changes
+
+```
+npm test
+# or
+npm run tests-only
+npm run lint
+```
+
+Push your changes
+
+```
+git push origin issue1234
+```
+
+Send the [pull request](https://docs.github.com/en/pull-requests), make requested changes, and get merged
+
+## Commit messages
+
+* Limit the first line of the commit message (message summary) to 72 characters or less
+* Use the present tense and imperative mood when providing a description of what you did
+* If your PR addresses an issue, reference it in the body of the commit message
+* See the rest of the conventions [here](https://gist.github.com/ljharb/772b0334387a4bee89af24183114b3c7)
+
+#### Commit message example
+
+```
+[Tag]: Short description of what you did
+
+Longer description here if necessary
+
+Fixes #1234
+```
+
+
+> **Note:**  Add co-authors to your commit message for commits with multiple authors
+
+```
+Co-authored-by: Name Here <email@here>
+```