docs(rosetta): add Rosetta documentation page

docs/README.md

@@ -66,6 +66,7 @@ aside: false
 - **[Specifications](./spec/)**: Specifications of modules and other parts of the Cosmos SDK.
 - **[SDK API Reference](https://godoc.org/github.com/cosmos/cosmos-sdk)**: Godocs of the Cosmos SDK.
 - **[REST and RPC Endpoints](https://cosmos.network/rpc/)**: List of endpoints to interact with a `gaia` full-node.
+- **[Rosetta API](./rosetta/)**: Rosetta API integration.
 
 ## Cosmos Hub
 

docs/rosetta/README.md

@@ -0,0 +1,50 @@
+<!--
+order: false
+parent:
+  order: 2
+-->
+
+# Rosetta
+
+This folder contains instructions about how to use the Coinbase Rosetta API integration.
+
+## Motivations and design
+
+For the motivation an design choices refer to the [ADR 035](../architecture/adr-035-rosetta-api-support.md)
+
+## Usage
+
+The Rosetta API server is a stand-alone server that connects to a node of a chain developed with the Cosmos-SDK. 
+
+To enable the Rosetta API server support it's required to Add the `RosettaCommand` to your application root command file.
+After the 
+
+```
+initRootCmd(rootCmd, encodingConfig)
+```
+
+line, add the following lines:
+
+```
+rootCmd.AddCommand(
+  server.RosettaCommand(encodingConfig.InterfaceRegistry, encodingConfig.Marshaler)
+)
+```
+
+
+The application root command file is in the server package in `github.com/cosmos/cosmos-sdk/server`.
+
+Since we’ve updated the Cosmos SDK to work with the Rosetta API, updating the application root command file is all you need to do.
+
+To run Rosetta in your application CLI, use the following command:
+`appd rosetta --help`.
+To test and run Rosetta API endpoints for applications that are running and exposed, use the following command:
+
+```
+appd rosetta
+     --blockchain "your application name (ex: gaia)"
+     --network "your chain identifier (ex: testnet-1)"
+     --tendermint "tendermint endpoint (ex: localhost:26657)"
+     --grpc "gRPC endpoint (ex: localhost:9090)"
+     --addr "rosetta binding address (ex: :8080)"
+```