docs: update API key generation steps (#1791)

packages/google-cloud-monitoring/README.md

@@ -49,8 +49,8 @@ If you are not running this client on Google Compute Engine, you need a Google D
 1. Visit the [Google Developers Console][dev-console].
 2. Create a new project or click on an existing project.
 3. Navigate to **APIs & auth** >  **Credentials** and then:
-  * If you want to use a new service account, click on **Create new Client ID** and select **Service account**. After the account is created, you will be prompted to download the JSON key file that the library uses to authenticate your requests.
-  * If you want to generate a new key for an existing service account, click on **Generate new JSON key** and download the JSON key file.
+  * If you want to use a new service account key, click on **Create credentials** and select **Service account key**. After the account key is created, you will be prompted to download the JSON key file that the library uses to authenticate your requests.
+  * If you want to generate a new service account key for an existing service account, click on **Generate new JSON key** and download the JSON key file.
 
 ``` js
 var projectId = process.env.GCLOUD_PROJECT; // E.g. 'grape-spaceship-123'