Merge pull request #2102 from QingWei-Li/update/template

Update github template

.github/ISSUE_TEMPLATE.md

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.github/PULL_REQUEST_TEMPLATE.md

@@ -2,5 +2,4 @@ Please makes sure these boxes are checked before submitting your PR, thank you!
 
 * [ ] Make sure you follow Element's [Contributing Guide](https://github.com/ElemeFE/element/blob/master/.github/CONTRIBUTING.md).
 * [ ] Make sure you are merging your commits to `dev` branch.
-* [ ] Rebase before creating a PR to keep commit history clear.
 * [ ] Add some descriptions and refer relative issues for you PR.