add quick example

tools/goctl/model/sql/template/delete.go

@@ -6,6 +6,7 @@ func (m *{{.upperStartCamelObject}}Model) Delete({{.lowerStartCamelPrimaryKey}}
 	if err!=nil{
 		return err
 	}{{end}}
+
 	{{.keys}}
     _, err {{if .containsIndexCache}}={{else}}:={{end}} m.Exec(func(conn sqlx.SqlConn) (result sql.Result, err error) {
 		query := ` + "`" + `delete from ` + "` +" + ` m.table + ` + " `" + ` where {{.originalPrimaryKey}} = ?` + "`" + `

tools/goctl/model/sql/template/errors.go

@@ -4,8 +4,5 @@ var Error = `package model
 
 import "github.com/tal-tech/go-zero/core/stores/sqlx"
 
-var (
-	ErrNotFound = sqlx.ErrNotFound
-)
-
+var ErrNotFound = sqlx.ErrNotFound
 `