added demo image and more detailed instructions to readme

assets/config.json

@@ -0,0 +1,28 @@
+{
+    "paddingVertical": "45px",
+    "paddingHorizontal": "45px",
+    "backgroundImage": null,
+    "backgroundImageSelection": null,
+    "backgroundMode": "color",
+    "backgroundColor": "rgba(31,129,109,1)",
+    "dropShadow": true,
+    "dropShadowOffsetY": "12px",
+    "dropShadowBlurRadius": "22px",
+    "theme": "nord",
+    "windowTheme": "none",
+    "language": "text",
+    "fontFamily": "Hack",
+    "fontSize": "14px",
+    "lineHeight": "150%",
+    "windowControls": true,
+    "widthAdjustment": true,
+    "lineNumbers": false,
+    "firstLineNumber": 1,
+    "exportSize": "4x",
+    "watermark": false,
+    "squaredImage": false,
+    "hiddenCharacters": false,
+    "name": "",
+    "width": 680,
+    "highlights": null
+}