update PR template (#827)

Enable to distinguish between updating documents directly related to
Explorer and translation work, as translation activities for this
repository are increasing.

### Type of Change

- [x ] Documentation Updates

.github/pull_request_template.md

@@ -28,6 +28,7 @@ Please check relevant options, delete irrelevant ones.
 - [ ] Refactor (non-breaking change that only restructures code)
 - [ ] Tests (You added tests for code that already exists, or your new feature included in this PR)
 - [ ] Documentation Updates
+- [ ] Translation Updates
 - [ ] Release
 
 ### TypeScript/Hooks Update