DOC Increase prominence of starting from existing issues (scikit-learn#31660)

Co-authored-by: Stefanie Senger <91849487+StefanieSenger@users.noreply.github.com>

Author: betatim

CONTRIBUTING.md

@@ -7,17 +7,14 @@ The latest contributing guide is available in the repository at
 
 https://scikit-learn.org/dev/developers/contributing.html
 
-There are many ways to contribute to scikit-learn, with the most common ones
-being contribution of code or documentation to the project. Improving the
-documentation is no less important than improving the library itself. If you
-find a typo in the documentation, or have made improvements, do not hesitate to
-send an email to the mailing list or preferably submit a GitHub pull request.
-Documentation can be found under the
-[doc/](https://github.com/scikit-learn/scikit-learn/tree/main/doc) directory.
-
-But there are many other ways to help. In particular answering queries on the
-[issue tracker](https://github.com/scikit-learn/scikit-learn/issues),
-investigating bugs, and [reviewing other developers' pull
+There are many ways to contribute to scikit-learn. Improving the
+documentation is no less important than improving the code of the library
+itself. If you find a typo in the documentation, or have made improvements, do
+not hesitate to create a GitHub issue or preferably submit a GitHub pull request.
+
+There are many other ways to help. In particular [improving, triaging, and
+investigating issues](https://github.com/scikit-learn/scikit-learn/issues),
+and [reviewing other developers' pull
 requests](https://scikit-learn.org/dev/developers/contributing.html#code-review-guidelines)
 are very valuable contributions that decrease the burden on the project
 maintainers.

doc/developers/contributing.rst

@@ -11,9 +11,9 @@ contribute. It is hosted on https://github.com/scikit-learn/scikit-learn.
 The decision making process and governance structure of scikit-learn is laid
 out in :ref:`governance`.
 
-Scikit-learn is somewhat :ref:`selective <selectiveness>` when it comes to
-adding new algorithms, and the best way to contribute and to help the project
-is to start working on known issues.
+Scikit-learn is :ref:`selective <selectiveness>` when it comes to
+adding new algorithms and features. This means the best way to contribute
+and help the project is to start working on known issues.
 See :ref:`new_contributors` to get started.
 
 .. topic:: **Our community, our values**
@@ -47,20 +47,17 @@ welcome to post feature requests or pull requests.
 Ways to contribute
 ==================
 
-There are many ways to contribute to scikit-learn, with the most common ones
-being contribution of code or documentation to the project. Improving the
-documentation is no less important than improving the library itself.  If you
-find a typo in the documentation, or have made improvements, do not hesitate to
-create a GitHub issue or preferably submit a GitHub pull request.
-Full documentation can be found under the doc/ directory.
+There are many ways to contribute to scikit-learn. Improving the
+documentation is no less important than improving the code of the library
+itself. If you find a typo in the documentation, or have made improvements, do
+not hesitate to create a GitHub issue or preferably submit a GitHub pull request.
 
-But there are many other ways to help. In particular helping to
+There are many ways to help. In particular helping to
 :ref:`improve, triage, and investigate issues <bug_triaging>` and
 :ref:`reviewing other developers' pull requests <code_review>` are very
-valuable contributions that decrease the burden on the project
-maintainers.
+valuable contributions that move the project forward.
 
-Another way to contribute is to report issues you're facing, and give a "thumbs
+Another way to contribute is to report issues you are facing, and give a "thumbs
 up" on issues that others reported and that are relevant to you.  It also helps
 us if you spread the word: reference the project from your blog and articles,
 link to it from your website, or simply star to say "I use it":
@@ -702,7 +699,8 @@ underestimate how easy an issue is to solve!
 Documentation
 =============
 
-We are glad to accept any sort of documentation:
+We welcome thoughtful contributions to the documentation and are happy to review
+additions in the following areas:
 
 * **Function/method/class docstrings:** Also known as "API documentation", these
   describe what the object does and detail any parameters, attributes and