Update README.md

Signed-off-by: Octavian Purdila <tavi@cs.pub.ro>

README.md

@@ -1 +1,36 @@
-# msfs-websim
+# msfs-websim
+
+A web based simulator for Microsoft Flght Simulator's html gauges /
+avionics. It runs in a browser and supports javascript debugging and
+inspection via the browser devtool.
+
+https://user-images.githubusercontent.com/213300/103544735-39238200-4ea9-11eb-93f3-69dd85c6d78f.mp4
+
+Prerequisites
+-------------
+
+[node.js and npm](https://docs.npmjs.com/downloading-and-installing-node-js-and-npm), 
+Chrome (other browsers may work but they were not tested) and a
+*Steam* version of MSFS.
+
+MSFS Steam is required because we need to access html/js files in the
+base install and in the MS store version the base install files are
+not readable (even with admin rights).
+
+Setup
+-----
+
+1. Run `npm install` to install dependency packages
+2. Set the following configuration parameters with npm config set
+msfs-websim:<param>:
+
+   * msfs_install_dir - base install dir for MSFS
+     (e.g. D:/steam/steamapps/common/MicrosoftFlightSimulator/)
+
+   * msfs_packages_dir - packages dir for MSFS
+
+Run
+----
+
+1. Run `npm start`
+2. Point your browser at http://localhost:8080