Update reference documentation for uuidRepresentation setting

JAVA-3516

Author: jyemin

docs/reference/content/driver/tutorials/databases-collections.md

@@ -200,4 +200,12 @@ MongoDatabase database = client.getDatabase("mydb")
 // or per collection
 MongoCollection<Document> collection = database.getCollection("mycoll")
                                                .withCodecRegistry(codecRegistry);
-```
+```   
+
+{{% note %}}
+Starting with the 3.12 release of the driver, you can also change the encoding of `UUID` instances via the `uuidRepresentation` property of
+`MongoClientSettings`.  See 
+[`MongoClientSettings.getUuidRepresentation`]({{<apiref "com/mongodb/MongoClientSettings.html#getUuidRepresentation()">}}) for
+details.
+{{% /note %}}
+

docs/reference/content/upgrading.md

@@ -7,6 +7,24 @@ title = "Upgrade Considerations"
   pre = "<i class='fa fa-level-up'></i>"
 +++
 
+## Upgrading from 3.11.x
+
+In the upcoming 4.0 release, all deprecated API elements except those documented as "not currently scheduled for removal" will be removed.
+Currently the only deprecated API elements _not_ scheduled for removal are:
+
+* [`Mongo.getDB`]({{<apiref "com/mongodb/Mongo.html#getDB-java.lang.String-">}})
+* [`JsonMode.STRICT`]({{<apiref "org/bson/json/JsonMode.html#STRICT">}})
+
+To prepare for the 4.0 release, please compile with deprecation warnings enabled and replace all usage of deprecated API elements with their
+recommended replacements.
+
+Also, note that the 3.12 release (which includes support for MongoDB 4.2) will be the last release that is compatible with *Java 6
+or Java 7*.  The 4.0 Java driver will require a minimum of Java 8. The 3.11 release will also be the last non-patch release in the 3.x
+line. In particular, support for MongoDB 4.4 will only be made available via a 4.x driver release.
+
+The 3.12 release is binary and source compatible with the 3.11 release, except for methods that have been added to interfaces that
+have been marked as unstable, and changes to classes or interfaces that have been marked as internal or annotated as Beta.
+
 ## Upgrading from 3.10.x
 
 Please note that the 3.11 driver enables both retryable reads and retryable writes by default, so users upgrading to the 3.11 driver may
@@ -21,11 +39,7 @@ Currently the only deprecated API elements _not_ scheduled for removal are:
 To prepare for the 4.0 release, please compile with deprecation warnings enabled and replace all usage of deprecated API elements with their
 recommended replacements.
 
-Also, note that the 3.11 release (which includes support for MongoDB 4.2) will be the last release that is compatible with *Java 6
-or Java 7*.  The 4.0 Java driver will require a minimum of Java 8. The 3.11 release will also be the last non-patch release in the 3.x
-line. In particular, support for MongoDB 4.4 will only be made available via a 4.x driver release.
-
-The 3.11 release is binary and source compatible with the 3.9 release, except for methods that have been added to interfaces that
+The 3.11 release is binary and source compatible with the 3.10 release, except for methods that have been added to interfaces that
 have been marked as unstable, and changes to classes or interfaces that have been marked as internal or annotated as Beta.
 
 ## Upgrading from 3.9.x

docs/reference/content/whats-new.md

@@ -7,6 +7,27 @@ title = "What's New"
   pre = "<i class='fa fa-level-up'></i>"
 +++
 
+## What's new in 3.12
+
+This release fully supports all MongoDB releases from versions 2.6 to 4.2. Key new features of the 3.11 Java driver release include:
+
+### Security improvements
+
+Client-side field level encryption is supported. Automatic encryption and decryption is available for users of
+[MongoDB Enterprise Advanced](https://www.mongodb.com/products/mongodb-enterprise-advanced), while explicit encryption and decryption is
+available for users of MongoDB Community.
+
+See [Client-side Encryption]({{<ref "driver/tutorials/client-side-encryption.md">}}) for further details.
+
+### Improved interoperability when using the native UUID type
+
+The driver now supports setting the BSON binary representation of `java.util.UUID` instances via a new `UuidRepresentation` property on
+`MongoClientSettings`.  The default representation has not changed, but it will in the upcoming 4.0 major release of the driver. 
+Applications that store UUID values in MongoDB can use this setting to easily control the representation in MongoDB without having to
+register a `Codec<Uuid>` in the `CodecRegistry`.  
+
+See [`MongoClientSettings.getUuidRepresentation`]({{<apiref "com/mongodb/MongoClientSettings.html#getUuidRepresentation()">}}) for details. 
+
 ## What's new in 3.11
 
 This release fully supports all MongoDB releases from versions 2.6 to 4.2. Key new features of the 3.11 Java driver release include: