Improved the issue templates.

.github/ISSUE_TEMPLATE/bug_report.md

@@ -4,17 +4,19 @@ about: Create a report to help us improve
 labels: bug
 ---
 
-# Checklist
+<!-- Note: Please follow the template to open a new issue, otherwise your question will probably be ignored. -->
+
+## Checklist
 <!-- Please complete the following list of tasks, and then check it by change the "[ ]" to "[x]" -->
 - [ ] I have read the [tutorials](https://chirpy.cotes.info/categories/tutorial/) and know the correct effect of the functional design.
 - [ ] There are no similar reports on existing issues (including closed ones).
 - [ ] I found the bug on the latest code of `master` branch.
 
 
-# Describe the bug
+## Describe the bug
 <!-- A clear and concise description of what the bug is. -->
 
-## To Reproduce
+**To Reproduce**
 
 Steps to reproduce the behavior:
 
@@ -24,24 +26,24 @@ Steps to reproduce the behavior:
 4. See error
 
 
-## Expected behavior
+**Expected behavior**
 <!-- A clear and concise description of what you expected to happen. -->
 
-## Screenshots
+**Screenshots**
 <!-- If applicable, add screenshots to help explain your problem. -->
 
-## Desktop:
+**Desktop**
 <!-- Please complete the following information -->
  - OS: [e.g. iOS]
  - Browser: [e.g. chrome, safari]
  - Version: [e.g. 22]
 
-## Smartphone:
+**Smartphone**
 <!-- please complete the following information -->
  - Device: [e.g. iPhone6]
  - OS: [e.g. iOS8.1]
  - Browser: [e.g. stock browser, safari]
  - Version: [e.g. 22]
 
-## Additional context
+**Additional context**
 <!-- Add any other context about the problem here. -->