Added actual readme content

Author: ryanplusplus

README.md

@@ -1,2 +1,19 @@
 # switch.lua
-Lua implementation of a switch statement
+Lua implementation of a switch statement. Supports an optional default case.
+
+## Example
+```lua
+local switch = require 'switch'
+
+switch('lua', {
+  goodbye = function(value)
+    ...
+  end,
+  hello = function(value)
+    ...
+  end,
+  [switch.default] = function(value)
+    ...
+  end
+})
+```