chore: add dev dependencies for cloud-rad ref docs (#461)

Author: fhinkel

packages/google-cloud-videointelligence/package.json

@@ -41,7 +41,9 @@
     "compile": "tsc -p . && cp -r protos build/",
     "compile-protos": "compileProtos src",
     "prepare": "npm run compile",
-    "precompile": "gts clean"
+    "precompile": "gts clean",
+    "api-extractor": "api-extractor run --local",
+    "api-documenter": "api-documenter yaml --input-folder=temp"
   },
   "dependencies": {
     "google-gax": "^2.1.0"
@@ -63,6 +65,8 @@
     "ts-loader": "^8.0.0",
     "typescript": "^3.8.3",
     "webpack": "^4.42.0",
-    "webpack-cli": "^3.3.11"
+    "webpack-cli": "^3.3.11",
+    "@microsoft/api-documenter": "^7.8.10",
+    "@microsoft/api-extractor": "^7.8.10"
   }
 }