third_party/binutils: clarify the procedure to upload the new binaries.

BUG=584828

Review URL: https://codereview.chromium.org/1691533002

Cr-Original-Commit-Position: refs/heads/master@{#374748}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 1ad0a1d1ba53cfe2a8ae3038be80f6ea4cdfadbb
diff --git a/README.chromium b/README.chromium
index 5f32f89..f5b5600 100644
--- a/README.chromium
+++ b/README.chromium
@@ -44,7 +44,9 @@
  * Remove any patches which have been merged upstream from build-all.sh
  * Update this README.chromium file
  * Run build-all.sh
- * Run upload.sh
+ * Run upload.sh. Note: you will need write access to
+   gs://chromium-binutils bucket on Google Cloud Storage. To get the
+   access, subscribe to the internal chrome-team mailing list.
  * Wait for goma to have new binutils deployed (see http://go/ma).
     Please notify {ukai,yyanagisawa,shinyak}@chromium.org and await
     confirmation.