Added documentation for the SET_PRIVATE_FIELDS_CONVENTION

JAVA-2648

Author: rozza

docs/reference/content/bson/pojos.md

@@ -315,6 +315,8 @@ The following Conventions are available from the [`Conventions`]({{<apiref "org/
   * The [`CLASS_AND_PROPERTY_CONVENTION`]({{<apiref "org/bson/codecs/pojo/Conventions.html#CLASS_AND_PROPERTY_CONVENTION">}}). Sets the 
         discriminator key if not set to `_t` and the discriminator value if not set to the ClassModels simple type name. Also, configures 
         the PropertyModels. If the `idProperty` isn't set and there is a property named `_id` or `id` then it will be marked as the `idProperty`.
+  * The [`SET_PRIVATE_FIELDS_CONVENTION`]({{<apiref "org/bson/codecs/pojo/Conventions.html#SET_PRIVATE_FIELDS_CONVENTION">}}).  Enables 
+        private fields to be set directly using reflection, without the need of a setter method. Note this convention is not enabled by default.
   * The [`DEFAULT_CONVENTIONS`]({{<apiref "org/bson/codecs/pojo/Conventions.html#DEFAULT_CONVENTIONS">}}), a list containing the 
     `ANNOTATION_CONVENTION` and the `CLASS_AND_PROPERTY_CONVENTION`.
   * The [`NO_CONVENTIONS`]({{<apiref "org/bson/codecs/pojo/Conventions.html#NO_CONVENTIONS">}}) an empty list.

docs/reference/content/whats-new.md

@@ -48,6 +48,7 @@ The 3.6 release brings new improvements to the `PojoCodec`:
   * Support for custom Collection and Map implementations.
   * Improvements to the `BsonCreator` annotation, which now supports `@BsonId` and `@BsonProperty` with values that represent the read name of the property.
   * A new [`PropertyCodecProvider`]({{<apiref "org/bson/codecs/pojo/PropertyCodecProvider">}}) API, allowing for easy and type-safe handling of container types.
+  * Added the [`SET_PRIVATE_FIELDS_CONVENTION`]({{<apiref "org/bson/codecs/pojo/Conventions.html#SET_PRIVATE_FIELDS_CONVENTION">}}) convention.
 
 The MongoDB Java drivers team would like to thank both [Joseph Florencio](https://github.com/jflorencio) and [Qi Liu](https://github.com/visualage)
 for their excellent contributions to the PojoCodec.