docs: Update README to Point to Newer Instructions (#1861)

* Update README.md

Remove mention of service account key download and point to correct place for ADC setup.

* chore: use readme-partials.yaml

---------

Co-authored-by: Daniel Bankhead <[email protected]>
Co-authored-by: d-goog <[email protected]>

Author: piaxc

.readme-partials.yaml

@@ -13,20 +13,12 @@ body: |-
   - [Downscoped Client](#downscoped-client) - Use Downscoped Client with Credential Access Boundary to generate a short-lived credential with downscoped, restricted IAM permissions that can use for Cloud Storage.
 
   ## Application Default Credentials
-  This library provides an implementation of [Application Default Credentials](https://cloud.google.com/docs/authentication/getting-started) for Node.js. The [Application Default Credentials](https://cloud.google.com/docs/authentication/getting-started) provide a simple way to get authorization credentials for use in calling Google APIs.
 
-  They are best suited for cases when the call needs to have the same identity and authorization level for the application independent of the user. This is the recommended approach to authorize calls to Cloud APIs, particularly when you're building an application that uses Google Cloud Platform.
+  This library provides an implementation of [Application Default Credentials (ADC)](https://cloud.google.com/docs/authentication/application-default-credentials) for Node.js. ADC provides a simple way to get credentials for use in calling Google APIs. How you [set up ADC](https://cloud.google.com/docs/authentication/provide-credentials-adc) depends on the environment where your code is running.
 
-  Application Default Credentials also support workload identity federation to access Google Cloud resources from non-Google Cloud platforms including Amazon Web Services (AWS), Microsoft Azure or any identity provider that supports OpenID Connect (OIDC). Workload identity federation is recommended for non-Google Cloud environments as it avoids the need to download, manage and store service account private keys locally, see: [Workload Identity Federation](#workload-identity-federation).
+  ADC is best suited for cases when the call needs to have the same identity and authorization level for the application independent of the user. This is the recommended approach to authorize calls to Cloud APIs, particularly when you're building an application that uses Google Cloud Platform.
 
-  #### Download your Service Account Credentials JSON file
-
-  To use Application Default Credentials, You first need to download a set of JSON credentials for your project. Go to **APIs & Auth** > **Credentials** in the [Google Developers Console](https://console.cloud.google.com/) and select **Service account** from the **Add credentials** dropdown.
-
-  > This file is your *only copy* of these credentials. It should never be
-  > committed with your source code, and should be stored securely.
-
-  Once downloaded, store the path to this file in the `GOOGLE_APPLICATION_CREDENTIALS` environment variable.
+  Application Default Credentials also supports Workload Identity Federation to access Google Cloud resources from non-Google Cloud platforms including Amazon Web Services (AWS), Microsoft Azure or any identity provider that supports OpenID Connect (OIDC). Workload Identity Federation is recommended for non-Google Cloud environments as it avoids the need to download, manage and store service account private keys locally, see: [Workload Identity Federation](#workload-identity-federation).
 
   #### Enable the API you want to use
 

README.md

@@ -57,20 +57,11 @@ This library provides a variety of ways to authenticate to your Google services.
 - [Downscoped Client](#downscoped-client) - Use Downscoped Client with Credential Access Boundary to generate a short-lived credential with downscoped, restricted IAM permissions that can use for Cloud Storage.
 
 ## Application Default Credentials
-This library provides an implementation of [Application Default Credentials](https://cloud.google.com/docs/authentication/getting-started) for Node.js. The [Application Default Credentials](https://cloud.google.com/docs/authentication/getting-started) provide a simple way to get authorization credentials for use in calling Google APIs.
+This library provides an implementation of [Application Default Credentials (ADC)](https://cloud.google.com/docs/authentication/application-default-credentials) for Node.js. ADC provides a simple way to get credentials for use in calling Google APIs. How you [set up ADC](https://cloud.google.com/docs/authentication/provide-credentials-adc) depends on the environment where your code is running.
 
-They are best suited for cases when the call needs to have the same identity and authorization level for the application independent of the user. This is the recommended approach to authorize calls to Cloud APIs, particularly when you're building an application that uses Google Cloud Platform.
+ADC is best suited for cases when the call needs to have the same identity and authorization level for the application independent of the user. This is the recommended approach to authorize calls to Cloud APIs, particularly when you're building an application that uses Google Cloud Platform.
 
-Application Default Credentials also support workload identity federation to access Google Cloud resources from non-Google Cloud platforms including Amazon Web Services (AWS), Microsoft Azure or any identity provider that supports OpenID Connect (OIDC). Workload identity federation is recommended for non-Google Cloud environments as it avoids the need to download, manage and store service account private keys locally, see: [Workload Identity Federation](#workload-identity-federation).
-
-#### Download your Service Account Credentials JSON file
-
-To use Application Default Credentials, You first need to download a set of JSON credentials for your project. Go to **APIs & Auth** > **Credentials** in the [Google Developers Console](https://console.cloud.google.com/) and select **Service account** from the **Add credentials** dropdown.
-
-> This file is your *only copy* of these credentials. It should never be
-> committed with your source code, and should be stored securely.
-
-Once downloaded, store the path to this file in the `GOOGLE_APPLICATION_CREDENTIALS` environment variable.
+Application Default Credentials also supports Workload Identity Federation to access Google Cloud resources from non-Google Cloud platforms including Amazon Web Services (AWS), Microsoft Azure or any identity provider that supports OpenID Connect (OIDC). Workload Identity Federation is recommended for non-Google Cloud environments as it avoids the need to download, manage and store service account private keys locally, see: [Workload Identity Federation](#workload-identity-federation).
 
 #### Enable the API you want to use