docs: add README

Signed-off-by: TJ Hoplock <[email protected]>

README.md

@@ -0,0 +1,40 @@
+# Go slog-gokit Adapter
+
+This library provides a custom slog.Handler that wraps a go-kit Logger, so that loggers created via `slog.New()` chain their log calls to the internal go-kit Logger.
+
+## Install
+
+```bash
+go get github.com/tjhop/slog-gokit
+```
+
+## Example
+
+```go
+package main
+
+import (
+	"log/slog"
+	"os"
+
+	"github.com/go-kit/log"
+	slgk "github.com/tjhop/slog-gokit"
+)
+
+func main() {
+	// Take an existing go-kit/log Logger:
+	gklogger := log.NewLogfmtLogger(os.Stderr)
+
+	// Create an slog Logger that chains log calls to the go-kit/log Logger:
+	slogger := slog.New(slgk.NewGoKitHandler(gklogger, nil))
+	slogger.WithGroup("example_group").With("foo", "bar").Info("hello world")
+
+	// The slog Logger produced logs at slog.LevelInfo by default.
+	// Optionally create an slog.Leveler to dynamically adjust the level of
+	// the slog Logger.
+	lvl := &slog.LevelVar{}
+	lvl.Set(slog.LevelDebug)
+	slogger = slog.New(slgk.NewGoKitHandler(gklogger, lvl))
+	slogger.WithGroup("example_group").With("foo", "bar").Info("hello world")
+}
+```