Move contributing information into README

In the most Maven project we have such information in README,
so to be consistent move it also here.

Use a similar format as in another project.

Author: slawekjaranowski

CONTRIBUTING.md

@@ -14,7 +14,7 @@
  See the License for the specific language governing permissions and
  limitations under the License.
 -->
-Maven Enforcer Plugin - The Loving Iron Fist of Maven™
+Contributing to [Maven Enforcer - The Loving Iron Fist of Maven™](https://maven.apache.org/enforcer/maven-enforcer-plugin)
 ======================================================
 
 [![Apache License, Version 2.0, January 2004](https://img.shields.io/github/license/apache/maven-enforcer.svg?label=License)][license]
@@ -27,57 +27,57 @@ The Enforcer plugin provides goals to control certain environmental constraints
 such as Maven version, JDK version and OS family along with many more built-in
 rules and user created rules.
 
-Documentation
--------------
-
-More information can be found on [Apache Maven Enforcer Plugin Homepage][enforcer-home].
-Question related to the usage of the Maven Enforcer Plugin should be posted on
-the [Maven User List][users-list].
-
-Where can I get the latest release?
------------------------------------
-You can download release source from our [download page][enforcer-download].
-
-Contributing
-------------
-
-We accept Pull Requests via GitHub. The [developer mailing list][dev-ml-list] is the
+You have found a bug, or you have an idea for a cool new feature? Contributing
+code is a great way to give something back to the open source community. Before
+you dig right into the code, there are a few guidelines that we need
+contributors to follow so that we can have a chance of keeping on top of
+things.
+
+Getting Started
+---------------
+
++ Make sure you have a [GitHub account](https://github.com/signup/free).
++ If you're planning to implement a new feature, it makes sense to discuss your changes
+  on the [dev list][ml-list] first.
+  This way you can make sure you're not wasting your time on something that isn't
+  considered to be in Apache Maven's scope.
++ Submit a ticket for your issue, assuming one does not already exist.
+  + Clearly describe the issue, including steps to reproduce when it is a bug.
+  + Make sure you fill in the earliest version that you know has the issue.
++ Fork the repository on GitHub.
+
+Making and Submitting Changes
+--------------
+
+We accept Pull Requests via GitHub. The [developer mailing list][ml-list] is the
 main channel of communication for contributors.  
 There are some guidelines which will make applying PRs easier for us:
-+ No tabs! Please use spaces for indentation.
-+ Respect the [code style][code-style].
-+ Create minimal diffs - disable on save actions like reformat source code or
-  organize imports. If you feel the source code should be reformatted create a
-  separate PR for this change.
-+ Provide JUnit/Invoker tests for your changes and make sure your changes don't break
-  any existing tests by running ```mvn -Prun-its verify```.
-
-If you plan to contribute on a regular basis, please consider filing a [contributor license agreement](https://www.apache.org/licenses/#clas).
-You can learn more about contributing via GitHub in our [contribution guidelines](CONTRIBUTING.md).
-
-
-License
--------
-This code is under the [Apache Licence v2][license]
-
-See the `NOTICE` file for required notices and attributions.
-
-Donations
----------
-You like Apache Maven? Then [donate back to the ASF](https://www.apache.org/foundation/contributing.html) to support the development.
-
-License
--------
-[Apache License, Version 2.0, January 2004][license]
++ Create a topic branch from where you want to base your work (this is usually the master branch).
+  Push your changes to a topic branch in your fork of the repository.
++ Make commits of logical units.
++ Respect the original code style: by using the same [codestyle][code-style],
+  patches should only highlight the actual difference, not being disturbed by any formatting issues:
+  + Only use spaces for indentation.
+  + Create minimal diffs - disable on save actions like reformat source code or organize imports.
+    If you feel the source code should be reformatted, create a separate PR for this change.
+  + Check for unnecessary whitespace with `git diff --check` before committing.
++ Make sure you have added the necessary tests (JUnit/IT) for your changes.
++ Run all the tests with `mvn -Prun-its verify` to assure nothing else was accidentally broken.
++ Submit a pull request to the repository in the Apache organization.
+
+If you plan to contribute on a regular basis, please consider filing a [contributor license agreement][cla].
+
+Additional Resources
+--------------------
+
++ [Contributing patches](https://maven.apache.org/guides/development/guide-maven-development.html#Creating_and_submitting_a_patch)
++ [Contributor License Agreement][cla]
++ [Apache Maven X Account](https://x.com/ASFMavenProject)
++ [Apache Maven Bluesky Account](https://bsky.app/profile/maven.apache.org)
++ [Apache Maven Mastodon Account](https://mastodon.social/deck/@[email protected])
 
-[home]: https://maven.apache.org/enforcer/maven-enforcer-plugin
 [license]: https://www.apache.org/licenses/LICENSE-2.0
 [build]: https://ci-maven.apache.org/job/Maven/job/maven-box/job/maven-enforcer/
 [test-results]: https://ci-maven.apache.org/job/Maven/job/maven-box/job/maven-enforcer/job/master/lastCompletedBuild/testReport/
-[build-status]: https://img.shields.io/jenkins/s/https/ci-maven.apache.org/job/Maven/job/maven-box/job/maven-enforcer/job/master.svg?
-[build-tests]: https://img.shields.io/jenkins/t/https/ci-maven.apache.org/job/Maven/job/maven-box/job/maven-enforcer/job/master.svg?
-[enforcer-home]: https://maven.apache.org/enforcer/maven-enforcer-plugin/
-[enforcer-download]: https://maven.apache.org/enforcer/download.cgi
-[users-list]: https://maven.apache.org/mailing-lists.html
-[dev-ml-list]: https://www.mail-archive.com/[email protected]/
+[ml-list]: https://maven.apache.org/mailing-lists.html
 [code-style]: https://maven.apache.org/developers/conventions/code.html