更新pr模板

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,3 +1,10 @@
 <!--
 Please target the `master` branch in priority.
--->
+
+In principle, a pull request only contains one commit, please squash your commits if your pull request have multiple commits.
+The best practice is to use `git commit --amend` for each commit after your first commit of this pr.
+
+原则上1个pr(Pull Request)只包含1个提交(Commit)。如过你的pr中有多个提交记录，请先进行压缩。
+最佳实践是在你的1个pr中的首次提交后的后续提交都使用`git commit --amend`进行修订提交。
+
+-->