[Doc] add weapp logo link

package.json

@@ -69,7 +69,7 @@
     "@babel/preset-env": "^7.5.5",
     "@babel/preset-typescript": "^7.3.3",
     "@types/jest": "^24.0.16",
-    "@vant/doc": "^2.3.6",
+    "@vant/doc": "^2.4.0",
     "@vant/eslint-config": "^1.2.4",
     "@vant/markdown-loader": "^2.2.0",
     "@vant/markdown-vetur": "^1.0.0",