update readme

Author: AhmadElsagheer

README.md

@@ -1,7 +1,58 @@
 # errorstack
 
-A lightweight package to get stacktrace of go errors. Designed to work with go1.21+
+A lightweight package to get stacktrace of go errors. Designed to work with `errors` standard package as of go1.20+. It also works well with `zap.Error` field to log error stacktrace.
 
 This is a fork of [pkg/errors](https://github.com/pkg/errors) which is archived now. The package has been simplified to provide only stacktrace functionality.
 
 ## Usage
+```go
+package main
+
+import (
+	"errors"
+	"fmt"
+
+	"github.com/ahmadelsagheer/errorstack"
+	"go.uber.org/zap"
+)
+
+func f1() error {
+	return f2()
+}
+
+func f2() error {
+	return f3()
+}
+
+func f3() error {
+	return errorstack.WithStack(errors.New("f3 error"))
+}
+
+func main() {
+
+	err := f1()
+
+	fmt.Printf("%v\n", err)
+	// f3 error
+	fmt.Printf("--\n")
+
+	fmt.Printf("%+v\n", err)
+	// main.f3
+	//         /Users/ahmad/codespace/errorstackexample/main.go:20
+	// main.f2
+	//         /Users/ahmad/codespace/errorstackexample/main.go:16
+	// main.f1
+	//         /Users/ahmad/codespace/errorstackexample/main.go:12
+	// main.main
+	//         /Users/ahmad/codespace/errorstackexample/main.go:25
+	// runtime.main
+	//         /usr/local/Cellar/go/1.21.0/libexec/src/runtime/proc.go:267
+	// runtime.goexit
+	//         /usr/local/Cellar/go/1.21.0/libexec/src/runtime/asm_amd64.s:1650
+	fmt.Printf("--\n")
+
+	logger := zap.NewExample()
+	logger.Error("error occurred", zap.Error(err))
+	// {"level":"error","msg":"error occurred","error":"f3 error","errorVerbose":"f3 error\nmain.f3\n\t/Users/ahmad/codespace/errorstackexample/main.go:20\nmain.f2\n\t/Users/ahmad/codespace/errorstackexample/main.go:16\nmain.f1\n\t/Users/ahmad/codespace/errorstackexample/main.go:12\nmain.main\n\t/Users/ahmad/codespace/errorstackexample/main.go:25\nruntime.main\n\t/usr/local/Cellar/go/1.21.0/libexec/src/runtime/proc.go:267\nruntime.goexit\n\t/usr/local/Cellar/go/1.21.0/libexec/src/runtime/asm_amd64.s:1650"}
+}
+```

go.mod

@@ -1,3 +1,3 @@
 module github.com/ahmadelsagheer/errorstack
 
-go 1.21.0
+go 1.20.0