Emphasize the importance of codec registry order

JAVA-3530

Author: jstewart148

docs/reference/content/driver-reactive/getting-started/quick-start-pojo.md

@@ -151,6 +151,13 @@ CodecRegistry pojoCodecRegistry = fromRegistries(MongoClientSettings.getDefaultC
                 fromProviders(PojoCodecProvider.builder().automatic(true).build()));
 ```
 
+{{% note %}}
+
+The registries are checked in order until one returns a codec for the requested class. 
+The `DefaultCodecRegistry` should be first in the list, and the `PojoCodecProvider` should always be the last `CodecProvider` since it can provide a codec for almost any class.
+
+{{% /note %}}
+
 ### Using the CodecRegistry
 
 There are multiple ways to set the `pojoCodecRegistry` for use:

docs/reference/content/driver/getting-started/quick-start-pojo.md

@@ -144,6 +144,13 @@ CodecRegistry pojoCodecRegistry = fromRegistries(MongoClientSettings.getDefaultC
                 fromProviders(PojoCodecProvider.builder().automatic(true).build()));
 ```
 
+{{% note %}}
+
+The registries are checked in order until one returns a codec for the requested class. 
+The `DefaultCodecRegistry` should be first in the list, and the `PojoCodecProvider` should always be the last `CodecProvider` since it can provide a codec for almost any class.
+
+{{% /note %}}
+
 ### Using the CodecRegistry
 
 There are multiple ways to set the `pojoCodecRegistry` for use: