update issue template

.github/ISSUE_TEMPLATE/problem_report.md

@@ -1,6 +1,6 @@
 ---
-name: Bug report
-about: Bug report
+name: Problem report
+about: Problem report
 title: ''
 labels: ''
 assignees: ''
@@ -11,7 +11,7 @@ Note: if you do not provide all of the following information I will directly ign
 
 - Il2CppDumper version
 
-- Target Unity version
+- Target Unity version (optional)
 
 - Describe the issue
 

.github/ISSUE_TEMPLATE/problem_report_cn.md

@@ -1,6 +1,6 @@
 ---
-name: Bug提交
-about: 中文Bug提交
+name: 问题报告
+about: 中文问题报告
 title: ''
 labels: ''
 assignees: ''
@@ -11,7 +11,7 @@ assignees: ''
 
 - Il2CppDumper版本
 
-- 目标Unity版本
+- 目标Unity版本 (可以不填)
 
 - 问题描述