Add usage and configuration notes.

README.md

@@ -22,7 +22,28 @@ Installation
 Usage
 -----
 
-TODO
+Build a JavaScript API client with a given spec:
+
+    swaggy-c --api-spec /path/to/spec.yaml
+
+The generated JavaScript client will then be written to `<out_dir>/<lang>/` directory.
+
+Build the client using Swagger CodeGen CLI jar:
+
+    swaggy-c --jar /path/to/swagger-codegen-cli.jar --api-spec /path/to/spec.yaml
+
+Build the client using specific configuration, output, and log directories:
+
+    swaggy-c --conf-dir /path/to/conf/ --out-dir /path/to/generated/ --log-dir /path/to/log --api-spec /path/to/spec.yaml
+
+Build the client and supress Swagger CodeGen CLI command output:
+
+    swaggy-c --quiet --api-spec /path/to/spec.yaml
+
+Configuration
+-------------
+
+Swagger CodeGen language configuration file should be placed at `<conf_dir>/<lang>.json` .
 
 Colophon
 --------
@@ -41,4 +62,4 @@ Related Projects:
 
 * [packer-swaggy-c](http://github.com/cliffano/packer-swaggy-c) - Packer builder of a Docker image that contains most languages supported by Swagger CodeGen
 * [swaggy-jenkins](http://github.com/cliffano/swaggy-jenkins) - Generated Jenkins API clients based on OpenAPI spec
-* [swaggy-jenkins-cli](http://github.com/cliffano/swaggy-jenkins-cli) - CLI utility tool for Swaggy Jenkins
+* [swaggy-jenkins-cli](http://github.com/cliffano/swaggy-jenkins-cli) - CLI utility tool for Swaggy Jenkins