Removed reduntant example from the AUTHENTICATION.md file and update …

…the README.md file

AUTHENTICATION.md

@@ -3,7 +3,7 @@
 The recommended way to authenticate to the Google Cloud PHP library is to use
 [Application Default Credentials (ADC)](https://cloud.google.com/docs/authentication/application-default-credentials),
 which discovers your credentials automatically, based on the environment where your code is running.
-To review all of your authentication options, see Credential lookup.
+To review all of your authentication options, [Credential Lookup](#credential-lookup).
 
 For more information about authentication at Google, see [the authentication guide](https://cloud.google.com/docs/authentication).
 Specific instructions and environment variables for each individual service are linked from the README documents listed below for each service.
@@ -23,9 +23,8 @@ The Google Cloud PHP library provides several mechanisms to configure your syste
 ### Google Cloud Platform environments
 
 While running on Google Cloud Platform environments such as Google Compute Engine, Google App Engine
-and Google Kubernetes Engine, no extra work is needed. The **Project ID** and **Credentials** and
-are discovered automatically from the attached service account. Code should be written as if already
-authenticated.
+and Google Kubernetes Engine, no extra work is needed. The **Credentials** and are discovered
+automatically from the attached service account. Code should be written as if already authenticated.
 
 For more information, see
 [Set up ADC for Google Cloud services](https://cloud.google.com/docs/authentication/provide-credentials-adc#attached-sa).
@@ -39,7 +38,7 @@ your environemnt variables are set in PHP, they must use
 ```php
 putenv("GOOGLE_APPLICATION_CREDENTIALS=" . __DIR__ . '/your-credentials-file.json');
 ```
-The **Project ID** and **Credentials JSON** can be placed in environment variables instead of
+The **Credentials JSON** can be placed in environment variables instead of
 declaring them directly in code.
 
 Here are the environment variables that Google Cloud PHP checks for project ID:
@@ -82,33 +81,6 @@ $video = new VideoIntelligenceServiceClient([
 ]);
 ```
 
-However, some clients use the `keyFile` or `keyFilePath` option:
-
-```php
-require 'vendor/autoload.php';
-
-use Google\Cloud\Storage\StorageClient;
-
-// Authenticating with keyfile data.
-$storage = new StorageClient([
-    'keyFile' => json_decode(file_get_contents('/path/to/keyfile.json'), true)
-]);
-
-// Authenticating with a keyfile path.
-$storage = new StorageClient([
-    'keyFilePath' => '/path/to/keyfile.json'
-]);
-
-// Providing the Google Cloud project ID.
-$storage = new StorageClient([
-    'projectId' => 'myProject'
-]);
-```
-
-Check the [client documentation][php-ref-docs] for the client library you're using.
-
-[php-ref-docs]: https://cloud.google.com/php/docs/reference
-
 ### Local ADC file
 
 This option allows for an easy way to authenticate in a local environment during development. If

README.md

@@ -15,9 +15,8 @@ If you need support for other Google APIs, please check out the [Google APIs Cli
 
 ## Quickstart
 
-It is required to have the credentials configured to make requests to the api using the clients. In
-this guide we'll focus on how to configure your client for local development using the Google Cloud
-CLI (`gcloud`).
+In this guide we'll focus on how to configure your client for local development using the Google
+Cloud CLI (`gcloud`).
 
 ### For local development:
 * Install the Google Cloud CLI.
@@ -52,6 +51,8 @@ Linux and MacOS:
 $HOME/.config/gcloud/application_default_credentials.json
 ```
 
+To read more about Authentication, see [AUTHENTICATION.md](AUTHENTICATION.md)
+
 ### Instantiating the client
 Once we have the `application_default_credentials.json` that we created on the previous step now we
 can instantiate a client which internally using the Google Auth library will take that file and use
@@ -114,9 +115,13 @@ for each service.
 
 ### Authentication
 
-Authentication is handled by the client library automatically. You just need to provide the authentication details when creating a client. Generally, authentication is accomplished using a Service Account. For more information on obtaining Service Account credentials, see our [Authentication Guide](https://cloud.google.com/docs/authentication/production#manually).
+Authentication is handled by the client once the environment is configured. Once youre credentials are created
+
+
+You just need to provide the authentication details when creating a client. Generally, authentication is accomplished using a Service Account. For more information on obtaining Service Account credentials see our [Authentication Guide](https://cloud.google.com/docs/authentication/production#manually).
 
-Once you've obtained your credentials file, it may be used to create an authenticated client.
+#### Note:
+Some clients accept the `keyFilePath` and `keyFile` configuration options pointing to the credentials file:
 
 ```php
 require 'vendor/autoload.php';
@@ -133,6 +138,16 @@ $cloud = new StorageClient([
     'keyFile' => json_decode(file_get_contents('/path/to/keyfile.json'), true)
 ]);
 ```
+A list of clients that accept these parameters are:
+- [Bigtable](https://github.com/googleapis/google-cloud-php-bigtable)
+- [Spanner](https://github.com/googleapis/google-cloud-php-spanner)
+- [Firestore](https://github.com/googleapis/google-cloud-php-firestore)
+- [Datastore](https://github.com/googleapis/google-cloud-php-datastore)
+- [Pubsub](https://github.com/googleapis/google-cloud-php-pubsub)
+
+We recommend to visit the Check the [client documentation][php-ref-docs] for the client library you're using for more in depth information.
+
+[php-ref-docs]: https://cloud.google.com/php/docs/reference
 
 If you do not wish to embed your authentication information in your application code, you may also make use of [Application Default Credentials](https://developers.google.com/identity/protocols/application-default-credentials).