wiki: fix link for sending a change when updating existing content

Change-Id: I6ab5fbe2649d69893314559d2e9661eaf6d3f049
GitHub-Last-Rev: c468dd2786319d639e145e7c560345a77be1e851
GitHub-Pull-Request: golang/wiki#31
Reviewed-on: https://go-review.googlesource.com/c/wiki/+/621918
Commit-Queue: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Auto-Submit: Ian Lance Taylor <iant@golang.org>

Contributing.md

diff --git a/Contributing.md b/Contributing.md
index 221714c..8b41286 100644
--- a/Contributing.md
+++ b/Contributing.md
@@ -10,7 +10,7 @@
 
 ## Reporting issues
 
-For issues related to existing contents, the preferred method of resolution is to send a [change](#sending-a-change-github).
+For issues related to existing contents, the preferred method of resolution is to send a [change](#updating-contents).
 
 However, if you would like to add a new page, please first open an issue in the [Go issue tracker](https://go.dev/issues/new?title=wiki:) with the prefix `wiki:` to propose the addition. Clearly state why the content does not fit into any of the existing pages.