doc/contribute: add examples for finding issues on the issue tracker

For contributors looking for new issues to contribute to it can be
difficult to find issues that need a fix and don't already have a fix
being considered. There are several labels that help guide the way
already, like `NeedsFix`, `HelpWanted`. But many issues with this label
will already have a CL. For new contributors this can be especially
difficult.

Fixes #26494

Change-Id: Ifd38ea65e362b4c580207a06f959646e49ac594f
GitHub-Last-Rev: 6d2b54447b2ee754a6d025f5de3ebd8326e035eb
GitHub-Pull-Request: golang/go#26516
Reviewed-on: https://go-review.googlesource.com/125355Reviewed-by: Andrew Bonventre <andybons@golang.org>
Run-TryBot: Andrew Bonventre <andybons@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

doc/contribute.html

@@ -292,6 +292,25 @@ Most issues will be marked with one of the following workflow labels:
 	</li>
 </ul>
 
+<p>
+You can use GitHub's search functionality to find issues to help out with. Examples:
+</p>
+
+<ul>
+	<li>
+	Issues that need investigation: <a href="https://github.com/golang/go/issues?q=is%3Aissue+is%3Aopen+label%3ANeedsInvestigation"><code>is:issue is:open label:NeedsInvestigation</code></a>
+	</li>
+	<li>
+	Issues that need a fix: <a href="https://github.com/golang/go/issues?q=is%3Aissue+is%3Aopen+label%3ANeedsFix"><code>is:issue is:open label:NeedsFix</code></a>
+	</li>
+	<li>
+	Issues that need a fix and have a CL: <a href="https://github.com/golang/go/issues?q=is%3Aissue+is%3Aopen+label%3ANeedsFix+%22golang.org%2Fcl%22"><code>is:issue is:open label:NeedsFix "golang.org/cl"</code></a>
+	</li>
+	<li>
+	Issues that need a fix and do not have a CL: <a href="https://github.com/golang/go/issues?q=is%3Aissue+is%3Aopen+label%3ANeedsFix+NOT+%22golang.org%2Fcl%22"><code>is:issue is:open label:NeedsFix NOT "golang.org/cl"</code></a>
+	</li>
+</ul>
+
 <h3 id="design">Open an issue for any new problem</h3>
 
 <p>