Add usage statement in README.md

README.md

@@ -1,6 +1,16 @@
 # ChronoZinc
 Small wrapper for `mzn-fzn` to benchmark MiniZinc models
 
-# TODO
+## Usage
+```
+chronozinc [config]* [models]* [data]*
+```
+Files are matched on extension:
+- Models: `.mzn`
+- Data: `.dzn`
+- Configuration: `.json`, `.toml`, `.yml` (viper extensions)
+
+## TODO
 - Remove all usage of `viper` from parsing and runtime packages
 - Provide separate the `run` and `parse` commands
+- MORE DOCUMENTATION!!!