bump(modern-web-guidance): ccb800c9 → 684ab9d7 (#4813)

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

.claude-plugin/marketplace.json

@@ -2235,7 +2235,7 @@
       "source": {
         "source": "url",
         "url": "https://github.com/GoogleChrome/modern-web-guidance.git",
-        "sha": "ccb800c9519286eaa7263d30c409e5bc9c0c6d9f"
+        "sha": "684ab9d7c6b78fc2cd5677912d874397cb2e5dfa"
       },
       "homepage": "https://goo.gle/modern-web-guidance"
     },