DOCSP-31430: Explain new API benefits (#436)

* DOCSP-31430: Explain new API benefits

* rewording

* build

* DOCSP-31430: Explain new API benefits

* rewording

* build

* addressing feedback

* vale suggestions

* typo

* typo

* tech feedback

* adding pojos

* wording fix

(cherry picked from commit 7286a63)

Author: norareidy

source/legacy.txt

@@ -16,8 +16,10 @@ Migrate from the Legacy API
 Overview
 --------
 
-In this section, you can identify the changes you need to make to migrate from
-the legacy API to the current API.
+On this page, you can identify the changes you must make to migrate from the
+legacy API to the current API. You can also learn about features unique to 
+the current {+driver-short+} and the benefits of migrating to the new API.
+
 
 The legacy API, packaged as the ``mongodb-driver-legacy`` JAR, contains
 the legacy synchronous Java driver and uses naming conventions used in earlier
@@ -37,6 +39,32 @@ In addition to updating your application to handle any necessary changes,
 always check for any other differences in options and return values before
 moving it to production.
 
+Current API Benefits
+--------------------
+
+You can continue to use the legacy API with each new {+mdb-server+} release.
+However, the legacy API does not support any updates introduced in {+mdb-server+}
+3.0 or later. Additionally, the legacy API lacks support for certain features
+of the current {+driver-short+}. Some features only available in the non-legacy
+API include:
+
+- **Change streams**, a {+mdb-server+} feature designed to monitor real-time
+  changes to a single collection, database, or deployment
+- **Multi-document ACID transactions**, which ensure atomicity of reads and
+  writes to multiple documents and allow for transactions across multiple
+  operations, collections, databases, documents, and shards
+- **Time series collections**, which store sequences of measurements over a
+  period of time and improve query efficiency for time series data
+- **Queryable Encryption**, which allows you to encrypt sensitive workloads
+  and to query the encrypted data
+- **Java records**, or concise Java classes that separate business logic from
+  data representation and reduce boilerplate code
+- **Native POJO support**, which provides automatic or custom mapping between
+  MongoDB documents and Java objects
+
+To learn about more features of the current API, see :ref:`java-whats-new`.
+
+ 
 API Changes
 -----------