Fix broken link in clang-format docs.

Change-Id: Ief702a3e9c02086063576532358da0eb5f12402c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1826058
Commit-Queue: Glen Robertson <glenrob@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Auto-Submit: Glen Robertson <glenrob@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#700049}

docs/updating_clang_format_binaries.md

@@ -98,7 +98,7 @@ Platform specific notes:
 Copy the binaries into your chromium checkout (under
 `src/buildtools/(win|linux64|mac)/clang-format(.exe?)`). For each binary, you'll
 need to run upload_to_google_storage.py according to the instructions in
-[README.txt](https://chromium.googlesource.com/chromium/buildtools/+/master/clang_format/README.txt).
+[README.txt](https://chromium.googlesource.com/chromium/src/+/master/buildtools/clang_format/README.txt).
 This will upload the binary into a publicly accessible google storage bucket,
 and update `.sha1` file in your Chrome checkout. You'll check in the `.sha1`
 file (but NOT the clang-format binary) into source control. In order to be able