Link to upstream in README.fuchsia

Upstream obtained from existing git remote

SEC-17

Change-Id: I4554971991b3c105dc003fa93f6160fb7d5a3980
diff --git a/README.fuchsia b/README.fuchsia
new file mode 100644
index 0000000..96f431d
--- /dev/null
+++ b/README.fuchsia
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+Upstream Git: https://chromium.googlesource.com/chromium/deps/icu