(DOCSP-44251) Removed EOL'd v2.20 and v2.19 (mongodb#262)

Co-authored-by: your proper name <your github email>

Author: elyse-mdb

source/whats-new.txt

@@ -30,8 +30,6 @@ Learn what's new in:
 * :ref:`Version 2.23 <version-2.23>`
 * :ref:`Version 2.22 <version-2.22>`
 * :ref:`Version 2.21 <version-2.21>`
-* :ref:`Version 2.20 <version-2.20>`
-* :ref:`Version 2.19 <version-2.19>`
 
 .. _upcoming-breaking-changes:
 
@@ -353,32 +351,4 @@ The 2.21 driver release includes the following new features:
 - Accepts options for Atlas Search sorting, tracking, and scoring.
 - Supports the Atlas Search :atlas:`embeddedDocument </atlas-search/embedded-document/>` operator.
 - Offers an API for Atlas Search index management.
-- Accepts anonymous types in the ``ObjectSerializer.DefaultAllowedTypes`` method.
-
-.. _version-2.20:
-
-What's New in 2.20
-------------------
-
-The 2.20 driver release includes the following new features:
-
-- Added full support for {+mdb-server+} version 7.0.0.
-- Added support for equality query types in Queryable Encryption GA.
-- Improvements to LINQ3 integration.
-- Improvements to serialization features.
-- Improvements to the logging framework.
-
-.. _version-2.19:
-
-What's New in 2.19
-------------------
-
-The 2.19 driver release includes the following new features:
-
-- The ``ObjectSerializer`` allows deserialization of only safe types, as determined by
-  the configurable ``AllowedTypes`` function.
-- Changed the default ``LinqProvider`` to LINQ3.
-- Added Atlas Search (``$search``) support to builders, aggregation pipelines, and LINQ3.
-- Added support for ``$bucket`` and ``$bucketAuto`` aggregation pipeline stages in LINQ3.
-- Added support for automatic KMS credentials for Azure VM Managed Identities.
-- Added native support for AWS IAM roles.
+- Accepts anonymous types in the ``ObjectSerializer.DefaultAllowedTypes`` method.