chore: release 2.0.0 (#23)

* updated CHANGELOG.md [ci skip]

* updated package.json [ci skip]

* updated samples/package.json

Co-authored-by: release-please[bot] <55107282+release-please[bot]@users.noreply.github.com>

Author: release-please[bot]

service-directory/snippets/package.json

@@ -13,7 +13,7 @@
     "test": "c8 mocha --timeout 600000 test/*.js"
   },
   "dependencies": {
-    "@google-cloud/service-directory": "^1.0.1",
+    "@google-cloud/service-directory": "^2.0.0",
     "eslint": "^7.0.0",
     "json-schema": "^0.2.5",
     "uuid": "^8.0.0"