build: create docs test npm scripts (#279)

Author: JustinBeckwith

packages/google-cloud-dialogflow/package.json

@@ -38,7 +38,9 @@
     "test": "npm run cover",
     "system-test": "mocha system-test/ --timeout 600000",
     "all-test": "npm test && npm run system-test && npm run samples-test",
-    "fix": "eslint '**/*.js' --fix"
+    "fix": "eslint '**/*.js' --fix",
+    "docs-test": "blcl docs -r --exclude www.googleapis.com",
+    "predocs-test": "npm run docs"
   },
   "dependencies": {
     "google-gax": "^0.25.0",
@@ -59,6 +61,7 @@
     "nyc": "^13.0.0",
     "power-assert": "^1.4.4",
     "prettier": "^1.7.4",
-    "through2": "^3.0.0"
+    "through2": "^3.0.0",
+    "broken-link-checker-local": "^0.2.0"
   }
 }