[fuzzer] Documentation: fix link for build configurations reference.

R=ahaas@chromium.org, ochang@chromium.org

Bug: Chromium:539572
Change-Id: I9e94a03c9173d0a17cb1a18dc8740972ff794368
Reviewed-on: https://chromium-review.googlesource.com/701601
Commit-Queue: Max Moroz <mmoroz@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48317}

test/fuzzer/README.md

@@ -79,7 +79,7 @@ new fuzzer to cluster fuzz.
    for more information.
 
 2. Compile the fuzzer in chromium (for different configurations see:
-   https://chromium.googlesource.com/chromium/src/+/master/testing/libfuzzer/reproducing.md):
+   https://chromium.googlesource.com/chromium/src/+/master/testing/libfuzzer/reference.md):
 
    * `gn gen out/libfuzzer '--args=use_libfuzzer=true is_asan=true is_debug=false enable_nacl=false'`