Updated README

Author: Piterden

README.md

@@ -15,6 +15,35 @@ Simple `image/jpeg` mime type rendered image on output.
 
 ## Usage
 
-
+Start:
+
+```sh
+npm run dev
+```
+
+#### URL structure
+
+```js
+const fen = 'rnbkqbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBKQBNR'
+
+const url = `http://localhost:3001/${fen}.jpg?${queryString}`
+```
+
+#### Query parameters
+
+| Name             | Type     | Default    | Description |
+| ---------------- | -------- | ---------- | ----------- |
+| **debug**        | `number` | `0`        | Turns on pure SVG markup |
+| **rotate**       | `number` | `0`        | Turns board to from black side view |
+| **arrows**       | `array`  | `[]`       | The array of arrows `/(?<fromFile>[a-h])(?<fromRank>\d)(?<toFile>[a-h])(?<toRank>\d)(?<color>[0-9a-f]{3,8})?/` |
+| **marks**        | `string` | `''`       | The comma separated list of mark/cross on piece |
+| **board_size**   | `number` | `512`      | Outer board size |
+| **marks_size**   | `number` | `5`        | Size of marks on pieceless squares |
+| **bg_color**     | `string` | `212121`   | Color of the background (the border around squares) of the board |
+| **text_color**   | `string` | `e5e5e5`   | Color of text around the board |
+| **cross_color**  | `string` | `ff2500`   | Color of cross fill |
+| **marks_color**  | `string` | `aaa23b`   | Color of marks on pieceless squares |
+| **b_cell_color** | `string` | `b58863`   | Color of black square |
+| **w_cell_color** | `string` | `f0d9b5`   | Color of white square |
 
 ## Develop

src/index.js

@@ -111,7 +111,7 @@ const renderSVG = (board, {
     .split('{{board}}').join(svgElements.join(''))
 }
 
-app.get('/:fen.jpeg', (req, res) => {
+app.get('/:fen.jpg', (req, res) => {
   const {
     debug = 0,
     rotate = 0,