docs(contributing): add link to Google Cloud Samples Style Guide (#1662)
docs(contributing): add link to Google Cloud Samples Style Guide (#1662)


GoogleCloudPlatform/php-docs-samples,GoogleCloudPlatform/php-docs-samples,GoogleCloudPlatform/php-docs-samples,GoogleCloudPlatform/php-docs-samples,GoogleCloudPlatform/php-docs-samples