Link to googleapis.dev documentation in READMEs. (#8705)

Author: busunkim96

packages/google-cloud-bigquery-datatransfer/README.rst

@@ -20,7 +20,7 @@ SaaS applications to Google BigQuery on a scheduled, managed basis.
 .. |compat_check_github| image:: https://python-compatibility-tools.appspot.com/one_badge_image?package=git%2Bgit%3A//github.com/googleapis/google-cloud-python.git%23subdirectory%3Dbigquery_datatransfer
    :target: https://python-compatibility-tools.appspot.com/one_badge_target?package=git%2Bgit%3A//github.com/googleapis/google-cloud-python.git%23subdirectory%3Dbigquery_datatransfer
 .. _BigQuery Data Transfer API: https://cloud.google.com/bigquery/transfer
-.. _Client Library Documentation: https://googleapis.github.io/google-cloud-python/latest/bigquery_datatransfer/index.html
+.. _Client Library Documentation: https://googleapis.dev/python/bigquery-datatransfer/latest
 .. _Product Documentation:  https://cloud.google.com/bigquery/docs/transfer-service-overview
 
 Quick Start
@@ -34,7 +34,7 @@ In order to use this library, you first need to go through the following steps:
 
 .. _Select or create a Cloud Platform project.: https://console.cloud.google.com/project
 .. _Enable the BigQuery Data Transfer API.:  https://cloud.google.com/bigquery/docs/transfer-service-overview
-.. _Setup Authentication.: https://googleapis.github.io/google-cloud-python/latest/core/auth.html
+.. _Setup Authentication.: https://googleapis.dev/python/google-api-core/latest/auth.html
 
 Installation
 ~~~~~~~~~~~~