fix: samples/documentation/dynamic-html/package.json to reduce vulner…

…abilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-EXPRESS-8161998

samples/documentation/dynamic-html/package.json

@@ -6,7 +6,7 @@
     "node": ">= 0.8.x"
   },
   "dependencies": {
-    "express": "3.x"
+    "express": "4.0.0"
   },
   "license": "Unlicense"
 }