Updated JSON API (markdown)

JSON-API.md

@@ -1,6 +1,20 @@
 Check back soon! This documentation is scheduled to be completed before the 3rd of April 2019
 
-Sample JSON API response (v0.8.4)
+Starting from version 0.8.4, WLED implements a powerful JSON API over HTTP.
+It is accessable using the `/json` subpage.
+
+### Obtaining light information
+Sending a GET request will return an object similar to the sample below.
+The response consists of four objects:
+- `state` contains the current state of the light. All values may be modified by the client (see below)
+- `info` contains general information about the device. No value can be modified using this API.
+- `effects` contains an array of the effect mode names
+- `palettes` contains an array of the palette names
+
+### Setting new values
+Sending a POST request to `/json/state` with (parts of) the state object will update the respective values.
+
+Sample JSON API response (v0.8.4):
 
 ```json
 {
@@ -11,32 +25,32 @@ Sample JSON API response (v0.8.4)
     "ps": -1,
     "pl": -1,
     "nl": {
-    "on": false,
-    "dur": 60,
-    "fade": true,
-    "tbri": 0
-  },
-  "udpn": {
-    "send": false,
-    "recv": true
-  },
-  "seg": [{
-    "start": 0,
-    "stop": 20,
-    "len": 20,
-    "col": [
-      [255, 160, 0, 0],
-      [0, 0, 0, 0],
-      [0, 0, 0, 0]
-    ],
-    "fx": 0,
-    "sx": 127,
-    "ix": 127,
-    "pal": 0,
-    "sel": true,
-    "rev": false,
-    "cln": -1
-  }]
+      "on": false,
+      "dur": 60,
+      "fade": true,
+      "tbri": 0
+    },
+    "udpn": {
+      "send": false,
+      "recv": true
+    },
+    "seg": [{
+      "start": 0,
+      "stop": 20,
+      "len": 20,
+      "col": [
+        [255, 160, 0, 0],
+        [0, 0, 0, 0],
+        [0, 0, 0, 0]
+      ],
+      "fx": 0,
+      "sx": 127,
+      "ix": 127,
+      "pal": 0,
+      "sel": true,
+      "rev": false,
+      "cln": -1
+    }]
   },
   "info": {
     "ver": "0.8.4",
@@ -61,7 +75,7 @@ Sample JSON API response (v0.8.4)
     "opt": 127,
     "brand": "WLED",
     "product": "DIY light",
-    "btype": "dev",
+    "btype": "src",
     "mac": "60019423b441"
   },
   "effects": [