API Documentation: Node API (#1655)

* Structure of the api doc

* Initial Node API Doc

doc/api/api.md

@@ -0,0 +1,20 @@
+# Grin API Documentation
+
+This document contains the documentation for the 3 Grin REST APIs. These endpoints can be grouped in two categories.
+
+## Node API
+
+This endpoint is used to query a node about various information on the blockchain, networks and peers. By default, this REST API will listen on `localhost:13413`. This API is started as the same time as the Grin node.
+To learn about what specific calls can be made read the [node API doc](node_api.md).
+
+## Wallet APIs
+
+### Foreign Wallet API
+
+The foreign API is an endpoint mainly designed to receiving grins through a network. This REST API can be started with the `grin wallet listen` command and by default will listen on `localhost:13415`.
+To learn about what specific calls can be made read the [wallet foreign API doc](wallet_foreign_api.md).
+
+### Wallet Owner API
+
+The wallet owner API is an endpoint to manage the user wallet: broadcast transaction, sign transaction, see the current balance... This REST API can be started with the `grin wallet owner_api` command and will listen on `localhost:13420`. This endpoint must **never** be exposed to the outside world.
+To learn about what specific calls can be made read the [wallet owner API doc](wallet_owner_api.md).

doc/table_of_contents.md

@@ -21,6 +21,7 @@
 
 ## Build and use
 
+- [api](api/api/md) - Explaining the different APIs in Grin and how to use them
 - [build](build.md) - Explaining how to build and run the Grin binaries
 - [release](release_instruction.md) - Instructions of making a release
 - [usage](usage.md) - Explaining how to use grin in Testnet3