docs: update README

README.md

@@ -1,7 +1,5 @@
 # signalk-autopilot
 
-[![Greenkeeper badge](https://badges.greenkeeper.io/sbender9/signalk-autopilot.svg)](https://greenkeeper.io/)
-
 <p align="center"><img src="./small-rayremote.png"></p>
 
 `signalk-autopilot` is composed of 2 modules: 
@@ -14,6 +12,8 @@ This current only supports Raymarine NMEA 2000 Autopilots, but I'll be adding su
 
 All messages to plugin are done using PUT requests. These can be done via HTTP or over WebSockets.
 
+Detailed info on [PUT](https://signalk.org/specification/1.3.0/doc/put.html) and [Request/Response](https://signalk.org/specification/1.3.0/doc/request_response.html)
+
 Http:
 
 ```
@@ -28,7 +28,7 @@ Delta:
 ```
 {
   "context": "vessels.self",
-  "correlationId": "184743-434373-348483",
+  "requestId": "184743-434373-348483",
   "put": {
     "path": "steering.autopilot.target.headingMagnetic",
     "value": 1.52
@@ -67,10 +67,9 @@ PUT http://localhost:3000/signalk/v1/api/vessels/self/steering/autopilot/actions
 }
 ```
 
-## Take a tack to port or starboard
+## Tack to port or starboard
 
 The `value` is `port` or `starboard`. 
-This command must be send only when your pilot is in `auto` or `wind` mode.
 
 ```
 PUT http://localhost:3000/signalk/v1/api/vessels/self/steering/autopilot/actions/tack