[licenses] Add path to license file in the README.fuchsia file.

This makes it easier for license checking tools to find
the correct license file.

More info: http://shortn/_S8Rzw4fSCw

Change-Id: I7b0e3a91e6bba9607e20b9b27e34b2f49eb73427
Reviewed-on: https://fuchsia-review.googlesource.com/c/third_party/tink/+/746003
Reviewed-by: Tamir Duberstein <tamird@google.com>
Commit-Queue: Jerry Belton <jcecil@google.com>
diff --git a/third_party/wycheproof/README.fuchsia b/third_party/wycheproof/README.fuchsia
index 149e1d6..7284294 100644
--- a/third_party/wycheproof/README.fuchsia
+++ b/third_party/wycheproof/README.fuchsia
@@ -1,3 +1,4 @@
 Name: Wycheproof
 URL: https://github.com/google/wycheproof
 LICENSE: Apache 2.0 license
+License File: LICENSE