Add a copy of NASM to util/bot/ in BoringSSL.

This is to transition BoringSSL's Windows build from Yasm to NASM. This
change itself is a no-op for now, but a later change to the BoringSSL
recipes will add a pair of standalone builders here. Then I'll get the
change I have lying around for Chromium moving.

Bug: chromium:766721
Change-Id: I4dca1c299f93bc5c01695983fe0478490c472deb
Reviewed-on: https://boringssl-review.googlesource.com/29324
Reviewed-by: Steven Valdez <svaldez@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>
diff --git a/util/bot/UPDATING b/util/bot/UPDATING
index f5a831b..b358f51 100644
--- a/util/bot/UPDATING
+++ b/util/bot/UPDATING
@@ -41,6 +41,16 @@
 
     The current revision is cmake-3.10.1-win32-x86.zip.
 
+nasm-win32.exe: Update to the appropriate release of NASM, found at
+    https://www.nasm.us/. Use the same version as Chromium, found at
+    https://chromium.googlesource.com/chromium/src/+/master/third_party/nasm/README.chromium
+    Extract nasm.exe from the download named nasm-VERSION-win32.zip.
+
+    The current revision is nasm-2.13.03-win32.zip.
+
+    TODO(davidben): The Chromium link currently does not work. It will get
+    filled in in the future. See https://crbug.com/766721.
+
 perl-win32.zip: Update to the latest 32-bit prebuilt "Portable" edition of
     Strawberry Perl, found at http://strawberryperl.com/releases.html. The
     download will be named strawberry-perl-VERSION-32bit-portable.zip.