fix: guideline email title (#328)

---------

Co-authored-by: imbajin <jin@apache.org>

content/cn/docs/contribution-guidelines/committer-guidelines.md

@@ -29,11 +29,15 @@ weight: 5
 
 下面是 HugeGraph 对应的邮件模板：(仅供参考)
 
-> 后续将使用 xxx 指代候选人名，一般 `xxx` 为一个容易读的名字 (例如 `Simon Jay`)，`ASF-INFRA` 建议**避免**使用不易读的 `ID` 直接作为邮件**人名代指** (例如**避免** `simon321` 或 `wh0isSim0n` 😄)
+> Note: 后续将使用 xxx 指代候选人名，一般 `xxx` 为一个容易读的名字 (例如 `Simon Jay`)
+>
+> `ASF-INFRA` 建议**避免**使用不易读的 `ID` 直接作为邮件**人名代指** (例如**避免** `simon321` 或 `wh0isSim0n` 😄)
+> 
+> 另发送邮件最好选择 **"纯文本"** 模式, 否则排版在 ASF Mail UI 中可能会乱
 
 ```markdown
 To: private@hugegraph.apache.org
-Subject: [VOTE] New committer: xxx
+Subject: [DISCUSS] XXX as a HugeGraph Committer Candidate
 
 Hi all:
 

content/en/docs/contribution-guidelines/committer-guidelines.md

@@ -28,11 +28,15 @@ The initiator of the discussion should clearly state the candidate's contributio
 
 Below is a template for HugeGraph emails: (For reference only)
 
-> The term `xxx` will be used to refer to the candidate. Typically, `xxx` represents an easily readable name (e.g., `Simon Jay`). ASF-INFRA recommends **avoiding** the use of less readable `ID` directly as a reference to the person in emails (e.g., avoid `simon321` or `wh0isSim0n` 😄).
+> Note: The term `xxx` will be used to refer to the candidate. Typically, `xxx` represents an easily readable name (e.g., `Simon Jay`). 
+> 
+> ASF-INFRA recommends **avoiding** the use of less readable `ID` directly as a reference to the person in emails (e.g., avoid `simon321` or `wh0isSim0n` 😄).
+>
+> In addition, it is best to choose the **"pure text"** mode, otherwise the typesetting may be chaotic in the ASF Mailing-list UI
 
 ```markdown
 To: private@hugegraph.apache.org
-Subject: [VOTE] New committer: xxx
+Subject: [DISCUSS] XXX as a HugeGraph Committer Candidate
 
 Hi all: