Add webapks-watchlist@chromium.org to add-to-homescreen watch list

TBR=loonybear@chromium.org

Change-Id: Iaa0e65037f861eb7c78bccfff44204cde5de77ff
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1727523Reviewed-by: Glenn Hartmann <hartmanng@chromium.org>
Commit-Queue: Glenn Hartmann <hartmanng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#682572}

WATCHLISTS

@@ -1912,7 +1912,8 @@
                       'yuzo+watch@chromium.org'],
     'add_to_homescreen': ['dominickn+watch-a2hs@chromium.org',
                           'hanxi+watch@chromium.org',
-                          'pkotwicz+watch@chromium.org'],
+                          'pkotwicz+watch@chromium.org',
+                          'webapks-watchlist@chromium.org'],
     'android_crash_reporting': ['asvitkine+watch@chromium.org',
                                 'wnwen+watch@chromium.org'],
     'android_crazy_linker': ['johnmaguire+watch@google.com'],