Update HTTP API docs (#1010)

book/src/http/node.md

@@ -0,0 +1,57 @@
+# Lighthouse REST API: `/node`
+
+The `/node` endpoints provide information about the lighthouse beacon node.
+
+## Endpoints
+
+HTTP Path | Description |
+| --- | -- |
+[`/node/version`](#nodeversion) | Get the node's version.
+[`/node/syncing`](#nodesyncing) | Get the node's syncing status.
+
+## `/node/version`
+
+Requests the beacon node's version.
+
+### HTTP Specification
+
+| Property | Specification |
+| --- |--- |
+Path | `/node/version`
+Method | GET
+JSON Encoding | String
+Query Parameters | None
+Typical Responses | 200
+
+### Example Response
+
+```json
+"Lighthouse-0.2.0-unstable"
+```
+
+## `/node/syncing`
+
+Requests the syncing status of the beacon node.
+
+### HTTP Specification
+
+| Property | Specification |
+| --- |--- |
+Path | `/node/syncing`
+Method | GET
+JSON Encoding | Object
+Query Parameters | None
+Typical Responses | 200
+
+### Example Response
+
+```json
+{
+	is_syncing: true,
+	sync_status: {
+	    starting_slot: 0,
+    	current_slot: 100,
+    	highest_slot: 200,
+	}
+}
+```