docs: add readme

README.md

@@ -1 +1,36 @@
-# sub-renamer
+# Sub-Renamer
+
+English | [简体中文](./README_ZH_CN.md)
+
+CLI tool to auto-rename subtitle files for matched video files.
+
+## Installation
+
+### Using `go`
+
+```sh
+$ go install https://github.com/acgtools/sub-renamer@latest
+```
+
+### Download from releases
+
+[Release page](https://github.com/acgtools/sub-renamer/releases)
+
+## Quick Start
+
+```sh
+$ sub-reanmer -h
+sub-renamer <video dir> <sub dir>
+
+Usage:
+  sub-renamer [flags]
+
+Flags:
+  -h, --help               help for sub-renamer
+      --log-level string   log level, options: debug, info, warn, error (default "info")
+```
+
+## Issue
+
+Feel free to create issues for reporting bugs or requesting new features. 
+

README_ZH_CN.md

@@ -0,0 +1,36 @@
+# Sub-Renamer
+
+English | [简体中文](./)
+
+自动为字幕文件匹配视频并重命名的 CLI 工具。
+
+## 安装
+
+### 使用 `go`
+
+```sh
+$ go install https://github.com/acgtools/sub-renamer@latest
+```
+
+### 从 Release 页面下载
+
+[Release page](https://github.com/acgtools/sub-renamer/releases)
+
+## 快速开始
+
+```sh
+$ sub-reanmer -h
+sub-renamer <video dir> <sub dir>
+
+Usage:
+  sub-renamer [flags]
+
+Flags:
+  -h, --help               help for sub-renamer
+      --log-level string   log level, options: debug, info, warn, error (default "info")
+```
+
+## Issue
+
+欢迎创建 issue 来报告 bug 或者 请求添加新特性。
+

cmd/root.go

@@ -48,7 +48,7 @@ var rootCmd = &cobra.Command{
 }
 
 func init() { //nolint:gochecknoinits
-	rootCmd.PersistentFlags().String("log-level", "info", "log level")
+	rootCmd.PersistentFlags().String("log-level", "info", "log level, options: debug, info, warn, error")
 
 	_ = viper.BindPFlag("log.level", rootCmd.PersistentFlags().Lookup("log-level"))
 }