Provide links to download GN binaries

We provide direct links for downloading GN release binaries from CIPD.

Change-Id: Id88991f0dbf490c05fe02b1e1327076690bcfd9d
Reviewed-on: https://gn-review.googlesource.com/c/3101
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: Petr Hosek <phosek@google.com>

README.md

diff --git a/README.md b/README.md
index 7e09117..b64b26b 100644
--- a/README.md
+++ b/README.md
@@ -6,6 +6,13 @@
 
 ## Getting started
 
+You can download the latest version of GN binary for
+[Linux](https://chrome-infra-packages.appspot.com/dl/gn/gn/linux-amd64/+/latest),
+[macOS](https://chrome-infra-packages.appspot.com/dl/gn/gn/mac-amd64/+/latest) and
+[Windows](https://chrome-infra-packages.appspot.com/dl/gn/gn/windows-amd64/+/latest).
+
+Alternatively, you can build GN from source:
+
     git clone https://gn.googlesource.com/gn
     cd gn
     python build/gen.py