Add cli documentation
* [Introduction](#introduction)
* [Core concepts](#core-concepts)
+* [Command line interface](#command-line-interface)
+ * [Global options](#global-options)
* [Configuration file](#configuration-file)
* [Syntax](#syntax)
* [File name](#file-name)
@@ -72,6 +74,30 @@ need any special development skills and offers easy configuration and integratio
| Backend Service(s) | External API or micro services where Couper fetches data from. |
| Validation | Couper supports validation of outgoing and incoming requests to and from the origin. |
+## Command Line Interface
+
+Couper is build as binary called `couper` with the following commands:
+
+| Command | Description |
+|:----------|:--------------------------------------------------|
+| `run` | Start the server with given configuration file. |
+| | *Note*: `run` options can also be configured with [settings](#settings-block) or related [environment variables](./../DOCKER.md).
+| `help` | Print the usage for the given command: `help run` |
+| `version` | Print the current version and build information. |
+
+### Global Options
+
+| Argument | Default | Environment | Description |
+|:----------|:-------------|:------------------|:------------------------------------------------------------------|
+| `-f` | `couper.hcl` | `COUPER_FILE` | File path to your Couper configuration file. |
+| `-watch` | `false` | `COUPER_WATCH` | Watch for configuration file changes and reload on modifications. |
+| `-watch-retries` | `5` | `COUPER_WATCH_RETRIES` | Maximal retry count for configuration reloads which could not bind the configured port. |
+| `-watch-retry-delay` | `500ms` | `COUPER_WATCH_RETRY_DELAY` | Delay duration before next attempt if an error occurs. |
+| `-log-format` | `common` | `COUPER_LOG_FORMAT` | Can be set to `json` output format. |
+| `-log-pretty` | `false` | `COUPER_LOG_PRETTY` | Option for `json` log format which pretty prints with basic key coloring. |
+
+*Note*: `log-format` and `log-pretty` also maps to [settings](#settings-block).
+
## Configuration file
### Syntax
