update readme file

README.md

@@ -1,3 +1,52 @@
-# web-advent-calendar
+# web advent calendar
 
-A dynamic php based advent calendar which can be easily configured via a json-config file
+A dynamic php based advent calendar which can be easily configured via a json-config file
+
+
+## Configuration
+
+There are two different and identical configuration files. One is the "calendar_prod.json" which is loaded by default and the other is the "calendar_dev.json" which is only loaded in development mode
+
+### Enable development-mode:
+
+Add the following switch at the end of the URL of the web application to activate the deverlopmend mode
+
+```/index.php?dev=1```
+
+### Configuration parameter
+
+Set width and height for the calendar:
+
+```json
+...
+"config": {
+    "calendarWidth": "472",
+    "calendarHeight": "827",
+	"useModal": "true",
+	"showExtras": "true"
+  },
+...
+```
+
+Add entries for the days
+```json
+...
+"entries": [
+    {
+      "unlockDate": "2020-12-19",
+      "doorWidth": "118",
+      "doorHeight": "118",
+      "positionTop": "0",
+      "positionLeft": "0",
+      "doorImageLeft": "images/19.png",
+      "backgroundImage": "images/background1x1.png",
+      "url": "adv19"
+    },
+    ...
+]
+...
+```
+
+## Browser support
+
+Unfortunately, older versions of Internet Explorer do not support CSS3 that well. The example calendar uses a fallback where the calendar doors are just hidden on hover.