From d00f49d9dd1e67953453035197a83db3a1634dca Mon Sep 17 00:00:00 2001
From: ttionya <git@ttionya.com>
Date: Wed, 24 Feb 2021 01:13:57 +0800
Subject: [PATCH] docs: update README

---
 README.md    | 4 +++-
 README_zh.md | 2 ++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 97df191..3e8a7d1 100644
--- a/README.md
+++ b/README.md
@@ -187,7 +187,9 @@ Default: `0`
 #### BACKUP_FILE_DATE_SUFFIX
 
 Each backup file is suffixed by default with `%Y%m%d`. If you back up your vault multiple times a day that suffix is not unique anymore.
-This environment variable allows you to append that date (`%Y%m%d${BACKUP_FILE_DATE_SUFFIX`) suffix in order to create a unique backup name. 
+This environment variable allows you to append that date (`%Y%m%d${BACKUP_FILE_DATE_SUFFIX`) suffix in order to create a unique backup name.
+
+Note that only numbers, upper and lower case letters, `-`, `_`, `%` are supported.
 
 Please use the [date man page](https://man7.org/linux/man-pages/man1/date.1.html) for the format notation.
 
diff --git a/README_zh.md b/README_zh.md
index 9f18578..cb17610 100644
--- a/README_zh.md
+++ b/README_zh.md
@@ -194,6 +194,8 @@ Rclone 远程名称，你可以自己修改命名。
 
 每个备份文件都默认添加 `%Y%m%d` 后缀。如果你在一天内多次进行备份，每次备份都会被覆盖之前同名的文件。这个环境变量允许你追加日期信息 (`%Y%m%d${BACKUP_FILE_DATE_SUFFIX`) 以便每次备份生成不同的文件。
 
+注意：只支持数字、大小写字母、`-`、`_` 和 `%`。
+
 在 [这里](https://man7.org/linux/man-pages/man1/date.1.html) 查看时间格式化说明。
 
 默认值：`''`