readme: Add Usage and Contributing sections

README.md

@@ -1,3 +1,94 @@
-# Upgrade
+# Upgrade-CLI
 
-Upgrade makes it easy to add an `upgrade` command to your cli.
+Upgrade-CLI makes it easy to add an `upgrade` command to your cli.
+
+## Install
+
+```sh
+go get github.com/getsavvyinc/upgrade-cli
+
+```
+
+## Usage
+
+[Savvy](https://github.com/getsavvyinc/savvy-cli) uses `upgrade-cli` to implement the [upgrade command](https://github.com/getsavvyinc/savvy-cli/blob/main/cmd/upgrade.go) in less than 10 lines of non boiler plate code
+
+```go
+package cmd
+
+import (
+	"context"
+	"os"
+
+	"github.com/getsavvyinc/savvy-cli/config"
+	"github.com/getsavvyinc/savvy-cli/display"
+	"github.com/getsavvyinc/upgrade-cli"
+	"github.com/spf13/cobra"
+)
+
+const owner = "getsavvyinc"
+const repo = "savvy-cli"
+
+// upgradeCmd represents the upgrade command
+var upgradeCmd = &cobra.Command{
+	Use:   "upgrade",
+	Short: "upgrade savvy to the latest version",
+	Long:  `upgrade savvy to the latest version`,
+	Run: func(cmd *cobra.Command, args []string) {
+		executablePath, err := os.Executable()
+		if err != nil {
+			display.Error(err)
+			os.Exit(1)
+		}
+		version := config.Version()
+
+		upgrader := upgrade.NewUpgrader(owner, repo, executablePath)
+
+		if ok, err := upgrader.IsNewVersionAvailable(context.Background(), version); err != nil {
+			display.Error(err)
+			return
+		} else if !ok {
+			display.Info("Savvy is already up to date")
+			return
+		}
+
+		display.Info("Upgrading savvy...")
+		if err := upgrader.Upgrade(context.Background(), version); err != nil {
+			display.Error(err)
+			os.Exit(1)
+		} else {
+			display.Success("Savvy has been upgraded to the latest version")
+		}
+	},
+}
+
+func init() {
+	rootCmd.AddCommand(upgradeCmd)
+}
+```
+
+## Requirements
+
+> `upgrade-cli` is fully compatible with releases generated using [goreleaser](https://github.com/goreleaser/goreleaser).
+
+`upgrade-cli` makes the following assumptions about Relase Assets.
+
+* The checksum file has a `checksums.txt` suffix
+* The checksum file format matches the example below:
+
+```sh
+6796a0fb64d0c78b2de5410a94749a3bfb77291747c1835fbd427e8bf00f6af3  savvy_darwin_arm64
+3853c410eeee629f71a981844975700b2925ac7582bf5559c384c391be8abbcb  savvy_darwin_x86_64
+00637eae6cf7588d990d64113a02caca831ea5391ef6f66c88db2dfa576ca6bd  savvy_linux_arm64
+1e9c98dbb0f54ee06119d957fa140b42780aa330d11208ad0a21c2a06832eca3  savvy_linux_i386
+3040ff4c07dda6c7ff65f9476b57277b14a72d0b33381b35aa8810df3e1785ea  savvy_linux_x86_64
+```
+* The URL to download a binary asset for a particular $os, $arch ends with `$os_$arch`
+
+## Contributing
+
+All contributions are welcome - bug reports, pull requests and ideas for improving the package.
+
+1. Join the `#upgrade-cli` channel on [Discord](https://getsavvy.so/discord)
+2. Open an [issue on GitHub](https://github.com/getsavvyinc/upgrade-cli/issues/new) to reports bugs or feature requests
+3. Please follow a ["fork and pull request"](https://docs.github.com/en/get-started/exploring-projects-on-github/contributing-to-a-project) workflow for submitting changes to the repository.