Python: Add wnwen@ to WATCHLIST

Create styleguide_python and add myself.

Bug: None
Change-Id: Idb174184d4b4f5214423a0d1f5bea88dacb34505
Reviewed-on: https://chromium-review.googlesource.com/c/1354325Reviewed-by: Eric Stevenson <estevenson@chromium.org>
Reviewed-by: agrieve <agrieve@chromium.org>
Commit-Queue: Peter Wen <wnwen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#611888}

WATCHLISTS

@@ -1506,6 +1506,9 @@
     'styleguide': {
       'filepath': '^styleguide/',
     },
+    'styleguide_python': {
+      'filepath': '^styleguide/python',
+    },
     'subresource_filter': {
       'filepath': 'subresource_filter|SubresourceFilter|url_pattern_index',
     },
@@ -2408,6 +2411,9 @@
     'styleguide': ['danakj+watch@chromium.org',
                    'jbroman+cpp@chromium.org',
                    'vmpstr+watch@chromium.org'],
+    'styleguide_python': ['agrieve+watch@chromium.org',
+                          'estevenson+watch@chromium.org',
+                          'wnwen+watch@chromium.org'],
     'subresource_filter': ['subresource-filter-reviews@chromium.org'],
     'supervised_users': [],
     'sync': ['sync-reviews@chromium.org'],