Adding a new RPC service to the list.

Adding Amazon Managed Blockchain to the RPC list

Author: evertonfraga

docs/pos/reference/rpc-endpoints.md

@@ -67,6 +67,7 @@ Public RPCs may have rate limits or traffic restrictions. For dedicated free RPC
 
 - [Alchemy](https://www.alchemy.com/)
 - [Allnodes](https://polygon.publicnode.com)
+- [Amazon Managed Blockchain](https://aws.amazon.com/managed-blockchain/)
 - [Ankr](https://www.ankr.com/)
 - [Blast (Bware Labs)](https://blastapi.io/)
 - [BlockPI](https://blockpi.io/)