Link to upstream in README.fuchsia

Upstream obtained from existing git remote

SEC-17

Change-Id: Ia138bd757da4a0dc2aaa98e60c174eea0ca3a6e3
diff --git a/README.fuchsia b/README.fuchsia
new file mode 100644
index 0000000..e9c2214
--- /dev/null
+++ b/README.fuchsia
@@ -0,0 +1 @@
+Upstream Git: https://github.com/google/re2