Point to SDK contributing guide

CONTRIBUTING.md

@@ -1,87 +1,15 @@
 Contributing to the Linter
 ==========================
 
-[![Build Status](https://github.com/dart-lang/linter/workflows/linter/badge.svg)](https://github.com/dart-lang/linter/actions)
-![GitHub contributors](https://img.shields.io/github/contributors/dart-lang/linter.svg)
+## [Repository has moved][]
 
+The Dart linter is now developed within the [Dart SDK][] repository,
+and can be found at https://github.com/dart-lang/sdk/tree/main/pkg/linter.
 
-Want to contribute? Great! First, read this page (including the small print at
-the end).
+To contribute changes, check out the [SDK Linter contribution guide][].
 
-### Before you contribute
+[Dart SDK]: https://github.com/dart-lang/sdk
+[SDK Linter contribution guide]: https://github.com/dart-lang/sdk/blob/main/pkg/linter/CONTRIBUTING.md
 
-_See also: [Dart's code of conduct](https://dart.dev/code-of-conduct)_
 
-Before we can use your code, you must sign the
-[Google Individual Contributor License Agreement](https://cla.developers.google.com/about/google-individual)
-(CLA), which you can do online. The CLA is necessary mainly because you own the
-copyright to your changes, even after your contribution becomes part of our
-codebase, so we need your permission to use and distribute your code. We also
-need to be sure of various other things—for instance that you'll tell us if you
-know that your code infringes on other people's patents. You don't have to sign
-the CLA until after you've submitted your code for review and a member has
-approved it, but you must do it before we can put your code into our codebase.
 
-Before you start working on a larger contribution, you should get in touch with
-us first through the issue tracker with your idea so that we can help out and
-possibly guide you. Coordinating up front makes it much easier to avoid
-frustration later on.
-
-### Code reviews
-All submissions, including submissions by project members, require review.
-
-### File headers
-All files in the project must start with the following header.
-
-    // Copyright (c) 2018, the Dart project authors.  Please see the AUTHORS file
-    // for details. All rights reserved. Use of this source code is governed by a
-    // BSD-style license that can be found in the LICENSE file.
-
-### Mechanics
-Contributing code is easy.
-
- * First, get the source by forking `https://github.com/dart-lang/linter` into your own GitHub account.
- * If you haven't configured your machine with an SSH key that's known to GitHub then follow the directions here: https://help.github.com/articles/generating-ssh-keys/.
- * `git clone git@github.com:<your_name_here>/linter.git`
- * `cd linter`
- * `git remote add upstream git@github.com:dart-lang/linter.git` (So that you fetch from the main repository, not your clone, when running git fetch et al.)
-
-To start working on a patch:
-
- * `git fetch upstream`
- * `git checkout upstream/main -b name_of_your_branch`
- * Hack away.  (Before committing, please be sure and run `dart format` on modified files; our build will fail if you don't!)
- * `git commit -a -m "<your informative commit message>"`
- * `git push origin name_of_your_branch`
-
-To send us a pull request:
-
- * `git pull-request` (if you are using [Hub](https://github.com/github/hub/)) or
-  go to `https://github.com/dart-lang/linter` and click the
-  "Compare & pull request" button
- * either explicitly name a reviewer in the GitHub UI or add their GitHub name in the pull request message body
-
-Please make sure all your checkins have detailed commit messages explaining the patch and if a PR is *not* ready to land, consider making it clear in the description and/or prefixing the title with "WIP".
-
-Please note that a few kinds of changes require a `CHANGELOG` entry. Notably, any change that:
-
-1. adds a new lint
-2. removes or deprecates a lint or
-3. fundamentally changes the semantics of an existing lint
-
-should have a short entry in the `CHANGELOG`. Feel free to bring up any questions in your PR.
-
-Once you've gotten an LGTM from a project maintainer, submit your changes to the
-`main` branch using one of the following methods:
-
-* Wait for one of the project maintainers to submit it for you.
-* Click the green "Merge pull request" button on the GitHub UI of your pull
-  request (requires commit access)
-* `git push upstream name_of_your_branch:main` (requires commit access)
-* Having done all this, please make sure we have a good email address so we can credit you in our `AUTHORS` file.
-* Thank you!
-
-### The small print
-Contributions made by corporations are covered by a different agreement than the
-one above, the
-[Software Grant and Corporate Contributor License Agreement](https://developers.google.com/open-source/cla/corporate).