Prepare for release (#2)

* README.md: add installation and usage instructions

* Publish artifacts to a corresponding GitHub release

* Create releases with GoReleaser

* CI: use only_if check and goreleaser:latest image

* README.md: clarify WIP status

.cirrus.yml

@@ -17,8 +17,8 @@ task:
   script: go test -v ./...
 
 task:
-  name: Build
-  depends_on:
-    - Lint
-    - Test
-  script: go build -v ./...
+  name: Release
+  only_if: $CIRRUS_TAG != ''
+  container:
+    image: goreleaser/goreleaser:latest
+  release_script: gorelease

.goreleaser.yml

@@ -0,0 +1,17 @@
+project_name: cirrus
+
+before:
+  hooks:
+    - go mod download
+
+builds:
+  - main: cmd/cirrus/main.go
+    env:
+      - CGO_ENABLED=0
+    goos:
+      - linux
+    goarch:
+      - amd64
+
+archives:
+  - format: zip

README.md

@@ -1,2 +1,29 @@
-# cirrus-cli
-CLI for executing Cirrus tasks locally
+# Cirrus CLI
+
+WIP CLI for executing Cirrus tasks locally. Currently can only validate Cirrus CI configuration file.
+
+## Installation
+
+### Releases
+
+Check the [releases page](https://github.com/cirruslabs/cirrus-cli/releases) for a pre-built `cirrus` binary for your platform.
+
+### Go
+
+If you have Go 1.14 installed, you can run:
+
+```
+go install github.com/cirruslabs/cirrus-cli/...
+```
+
+This will build and place the `cirrus` binary in `$GOPATH/bin`.
+
+To be able to run `cirrus` command from anywhere, make sure that the `$GOPATH/bin` directory is added to your `PATH` environment variable (see [article in the Go wiki](https://github.com/golang/go/wiki/SettingGOPATH) for more details).
+
+## Usage
+
+To validate a Cirrus CI configuration, simply switch to a directory where the `.cirrus.yml` is located and run:
+
+```
+cirrus validate
+```