Update README

Signed-off-by: Nick Young <ynick@vmware.com>

Author: youngnick

README.md

@@ -1,3 +1,37 @@
 # ir2proxy [![Build Status](https://travis-ci.com/projectcontour/ir2proxy.svg?branch=master)](https://travis-ci.com/projectcontour/ir2proxy) [![Go Report Card](https://goreportcard.com/badge/github.com/projectcontour/ir2proxy)](https://goreportcard.com/report/github.com/projectcontour/ir2proxy) ![GitHub release](https://img.shields.io/github/release/projectcontour/ir2proxy.svg) [![License](https://img.shields.io/badge/License-Apache%202.0-blue.svg)](https://opensource.org/licenses/Apache-2.0)
 
 ir2proxy is a tool to convert ir2proxy's IngressRoute resources to HTTPProxy resources.
+
+## Usage
+
+`ir2proxy` is intended for taking a yaml file containing one or more valid IngressRoute objects, and then outputting translated HTTPProxy objects to stdout.
+
+Logging is done to stderr.
+
+To use the tool, just run it with a filename as input.
+
+```sh
+$ ir2proxy basic.ingressroute.yaml
+---
+apiVersion: projectcontour.io/v1
+kind: HTTPProxy
+metadata:
+  name: basic
+  namespace: default
+spec:
+  routes:
+  - conditions:
+    - prefix: /
+    services:
+    - name: s1
+      port: 80
+  virtualhost:
+    fqdn: foo-basic.bar.com
+status:
+  currentStatus: ""
+  description: ""
+```
+
+## Installation
+
+Go to the [releases](https://github.com/projectcontour/ir2proxy/releases) page and download the latest version.