Update WATCHLIST wrt yangguo

R=jgruber@chromium.org

Change-Id: I49c08217d0c8e452afe84ad76ae6d60367802e82
Reviewed-on: https://chromium-review.googlesource.com/c/1348075Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57762}

WATCHLISTS

@@ -97,6 +97,7 @@
   'WATCHLISTS': {
     'api': [
       'adamk+watch@chromium.org',
+      'yangguo+watch@chromium.org',
     ],
     'csa': [
       'jgruber+watch@chromium.org',
@@ -106,11 +107,11 @@
     ],
     'snapshot': [
       'jgruber+watch@chromium.org',
-      'yangguo@chromium.org',
+      'yangguo+watch@chromium.org',
     ],
     'debugger': [
       'jgruber+watch@chromium.org',
-      'yangguo@chromium.org',
+      'yangguo+watch@chromium.org',
     ],
     'interpreter': [
       'rmcilroy@chromium.org',