DOCSP-43402: link to migration guide + clarify lang (mongodb#381)

* DOCSP-43402: link to migration guide + clarify lang

* MW PR fixes + link oidc

source/whats-new.txt

@@ -21,11 +21,12 @@ What's New
 
    To learn more about changes and updates between versions, you can
    read the `release notes
-   <https://github.com/mongodb/mongo-go-driver/tags>`__ published with the driver source code.
+   <https://github.com/mongodb/mongo-go-driver/tags>`__ published with
+   the driver source code.
 
 Learn what's new in:
 
-* :ref:`Version 2.0 <version-2.0>`
+* :ref:`Version 2.0 <golang-version-2.0>`
 * :ref:`Version 1.16 <version-1.16>`
 * :ref:`Version 1.15.1 <version-1.15.1>`
 * :ref:`Version 1.15 <version-1.15>`
@@ -46,17 +47,21 @@ Learn what's new in:
 * :ref:`Version 1.1 <version-1.1>`
 * :ref:`Version 1.0 <version-1.0>`
 
-.. _version-2.0:
+.. _golang-version-2.0:
 
 What's New in 2.0
 -----------------
 
-The 2.0 {+driver-short+} release supports various new features, provides
-a smoother timeout experience, and implements clearer, more idiomatic Go
+The 2.0 {+driver-short+} release supports OpenID Connect (OIDC)
+authentication, provides a smoother client-side operations timeout
+(CSOT) experience, and implements clearer, more idiomatic Go
 code by streamlining APIs, improving errors descriptions, and
 simplifying the driver package structure.
 
-In this section, you can learn more about these changes.
+You can learn more about these changes in this section, or by viewing
+the `v2.0 Migration Guide
+<https://github.com/mongodb/mongo-go-driver/blob/master/docs/migration-2.0.md>`__
+in the {+driver-short+} source code on GitHub.
 
 .. important:: Breaking Changes
 
@@ -99,6 +104,10 @@ In this section, you can learn more about these changes.
 
 This release includes the following improvements and fixes:
 
+- Support for OpenID Connect (OIDC) authentication. To learn more, see
+  the :ref:`golang-mongodb-oidc` section of the Enterprise
+  Authentication Mechanisms guide.
+
 - You can access the GridFS API from the ``mongo`` package. In previous
   versions, you could access GridFS functions from the separate ``gridfs``
   package, but this functionality is now merged with the main driver