README.md: Flesh out

README.md

@@ -1,3 +1,40 @@
 # fengari-node-cli
 
-The Lua command line application, but using fengari under node.js
+The Lua command line application, but using [fengari](http://fengari.io/) under [node.js](https://nodejs.org/)
+
+This project consists of `fengari` and `fengaric` command line applications that provide functionality equivalent to the [`lua`](http://www.lua.org/manual/5.3/manual.html#7) and [`luac`](https://www.lua.org/manual/5.3/luac.html) programs.
+
+## Installation
+
+Use `npm` or [`yarn`](http://yarnpkg.com/):
+
+```bash
+npm install -g fengari-node-cli
+```
+
+
+## Usage
+
+```
+usage: fengari [options] [script [args]]
+Available options are:
+  -e stat  execute string 'stat'
+  -i       enter interactive mode after executing 'script'
+  -l name  require library 'name'
+  -v       show version information
+  -E       ignore environment variables
+  --       stop handling options
+  -        stop handling options and execute stdin
+```
+
+```
+usage: fengaric [options] [filename]
+Available options are:
+  -l       list (use -l -l for full listing)
+  -o name  output to file 'name' (default is "fengaric.out")
+  -p       parse only
+  -s       strip debug information
+  -v       show version information
+  --       stop handling options
+  -        stop handling options and process stdin
+```