feat: update PR template to include documentation issue/PR link (#126)

Author: Ki-Seki

.github/PULL_REQUEST_TEMPLATE.md

@@ -3,26 +3,30 @@
 <!--
 Please include a summary of the changes below;
 Fill in the issue number that this PR addresses (if applicable);
+Fill in the related MemOS-Docs repository issue or PR link (if applicable);
 Mention the person who will review this PR (if you know who it is);
-Replace (summary), (issue), and (reviewer) with the appropriate information.
+Replace (summary), (issue), (docs-issue-or-pr-link), and (reviewer) with the appropriate information.
 
 请在下方填写更改的摘要；
 填写此 PR 解决的问题编号（如果适用）；
+填写相关的 MemOS-Docs 仓库 issue 或 PR 链接（如果适用）；
 提及将审查此 PR 的人（如果您知道是谁）；
-替换 (summary)、(issue) 和 (reviewer) 为适当的信息。
+替换 (summary)、(issue)、(docs-issue-or-pr-link) 和 (reviewer) 为适当的信息。
 -->
 
 Summary: (summary)
 
 Fix: #(issue)
 
+Docs Issue/PR: (docs-issue-or-pr-link)
+
 Reviewer: @(reviewer)
 
 ## Checklist:
 
 - [ ] I have performed a self-review of my own code | 我已自行检查了自己的代码
 - [ ] I have commented my code in hard-to-understand areas | 我已在难以理解的地方对代码进行了注释
 - [ ] I have added tests that prove my fix is effective or that my feature works | 我已添加测试以证明我的修复有效或功能正常
-- [ ] I have added necessary documentation (if applicable) | 我已添加必要的文档（如果适用）
+- [ ] I have created related documentation issue/PR in [MemOS-Docs](https://github.com/MemTensor/MemOS-Docs) (if applicable) | 我已在 [MemOS-Docs](https://github.com/MemTensor/MemOS-Docs) 中创建了相关的文档 issue/PR（如果适用）
 - [ ] I have linked the issue to this PR (if applicable) | 我已将 issue 链接到此 PR（如果适用）
 - [ ] I have mentioned the person who will review this PR | 我已提及将审查此 PR 的人