[docs] Update structure-aware-fuzzing link.

The document has been moved to the google/fuzzing GitHub repo.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@372423 91177308-0d34-0410-b5e6-96231b3b80d8

docs/LibFuzzer.rst

@@ -590,7 +590,7 @@ User-supplied mutators
 ----------------------
 
 LibFuzzer allows to use custom (user-supplied) mutators, see
-`Structure-Aware Fuzzing <https://github.com/google/fuzzer-test-suite/blob/master/tutorial/structure-aware-fuzzing.md>`_
+`Structure-Aware Fuzzing <https://github.com/google/fuzzing/blob/master/docs/structure-aware-fuzzing.md>`_
 for more details.
 
 Startup initialization