Update README.md

Author: 1997y1

README.md

@@ -34,3 +34,37 @@ work_2 ...
 work_1 ...
 :shutdown
 ```
+
+<br>
+
+## X errcause
+
+```go
+package main
+
+import (
+	"github.com/matsuwin/siggroup/x/errcause"
+	"github.com/pkg/errors"
+	"io/ioutil"
+)
+
+func mkError() error {
+	_, err := ioutil.ReadFile("xxx.txt")
+	return errors.New(err.Error())
+}
+
+func main() {
+	
+	// 错误恢复 recover call errcause.Keep
+	defer func() {
+		if ei := recover(); ei != nil {
+			errcause.Keep(ei)
+		}
+	}()
+
+	// 模拟一个错误抛出调用
+	if err := mkError(); err != nil {
+		panic(err)
+	}
+}
+```