Add linux_chromium_msan_rel_ng trybot to clang update instruction.

docs/updating_clang.md

Index: docs/updating_clang.md
diff --git a/docs/updating_clang.md b/docs/updating_clang.md
index 529dc2be3f1eb8566a52426da4567800f5209fd3..d8a8575a01d430498a79da72c822044847fbc074 100644
--- a/docs/updating_clang.md
+++ b/docs/updating_clang.md
@@ -17,8 +17,9 @@
     git cl try -m tryserver.chromium.linux -b linux_chromium_gn_dbg -b
     linux_chromium_chromeos_dbg_ng -b linux_chromium_asan_rel_ng -b
     linux_chromium_chromeos_asan_rel_ng -b android_clang_dbg_recipe -b
-    linux_chromium_trusty32_rel -b linux_chromium_rel_ng && git cl try -m
-    tryserver.blink -b linux_blink_rel`
+    linux_chromium_trusty32_rel -b linux_chromium_rel_ng -b
+    linux_chromium_msan_rel_ng && git cl try -m tryserver.blink -b
+    linux_blink_rel`
 1.  Commit roll CL from the first step
 1.  The bots will now pull the prebuilt binary, and goma will have a matching
     binary, too.