doc: fix link in contribute.html

Fixes #26611

Change-Id: I111152c7b1156a461c9ddeaf16d2fe7a2d5a00c1
GitHub-Last-Rev: 72090d539b5601b8c585628a11a99b03103d5a75
GitHub-Pull-Request: golang/go#26724
Reviewed-on: https://go-review.googlesource.com/126935Reviewed-by: Ian Lance Taylor <iant@golang.org>

doc/contribute.html

@@ -73,7 +73,7 @@ $ go-contrib-init
 <p>
 The rest of this chapter elaborates on these instructions.
 If you have completed the steps above (either manually or through the tool), jump to
-<a href="#making_a_change">Making a change</a>.
+<a href="#before_contributing">Before contributing code</a>.
 </p>
 
 <h3 id="google_account">Step 0: Select a Google Account</h3>