Add README

README.md

@@ -1 +1,64 @@
-# sd-step
+# sd-step
+[![Build Status][build-image]][build-url]
+[![Latest Release][version-image]][version-url]
+[![Go Report Card][goreport-image]][goreport-url]
+
+> Wrapper command of habitat for Screwdriver
+
+## Usage
+
+```bash
+$ go get github.com/screwdriver-cd/sd-step
+$ cd $GOPATH/src/github.com/screwdriver-cd/sd-step
+$ go build -a -o sd-step
+$ ./sd-step --help
+NAME:
+   sd-step - wrapper command of habitat for Screwdriver
+
+USAGE:
+   sd-step command arguments [options]
+
+VERSION:
+   0.0.0
+
+COMMANDS:
+     exec     Install and exec habitat package with pkg_name and command...
+     help, h  Shows a list of commands or help for one command
+
+GLOBAL OPTIONS:
+   --pkg-version value  Package version which also accepts semver expression
+   --hab-channel value  Install from the specified release channel (default: "stable")
+   --help, -h           show help
+   --version, -v        print the version
+
+COPYRIGHT:
+   (c) 2017 Yahoo Inc.
+$ ./sd-step exec core/node "node -v"
+v8.9.0
+$ ./sd-step exec --pkg-version "~6.11.0" core/node "node -v"
+v6.11.5
+$ ./sd-step exec --pkg-version "^6.0.0" core/node "node -v"
+v6.11.5
+$ ./sd-step exec --pkg-version "4.2.6" core/node "node -v"
+v4.2.6
+$ ./sd-step exec --pkg-version "~6.9.0" --hab-channel "unstable" core/node "node -v"
+v6.9.5
+```
+
+## Testing
+
+```bash
+$ go get github.com/screwdriver-cd/sd-step
+$ go test -cover github.com/screwdriver-cd/sd-step/...
+```
+
+## License
+
+Code licensed under the BSD 3-Clause license. See LICENSE file for terms.
+
+[version-image]: https://img.shields.io/github/tag/screwdriver-cd/sd-step.svg
+[version-url]: https://github.com/screwdriver-cd/sd-step/releases
+[build-image]: https://cd.screwdriver.cd/pipelines/150/badge
+[build-url]: https://cd.screwdriver.cd/pipelines/150
+[goreport-image]: https://goreportcard.com/badge/github.com/Screwdriver-cd/sd-step
+[goreport-url]: https://goreportcard.com/report/github.com/Screwdriver-cd/sd-step