Improved the community docs.

- Added the PR template & code of conduct
- Improved the issue templates.

.github/ISSUE_TEMPLATE/feature_request.md

@@ -4,18 +4,25 @@ about: Suggest an idea for this project
 labels: enhancement
 ---
 
-<!-- Please make sure your request does not appear in other existing issues (including closed ones). Thanks for your cooperation. Now, I can't wait to listen your idea! -->
+# Checklist
+<!-- Please complete the following list of tasks, and then check it by change the "[ ]" to "[x]" -->
+- [ ] I have read the [contributing guidelines](https://github.com/cotes2020/jekyll-theme-chirpy/blob/master/.github/CONTRIBUTING.md).
+- [ ] There are no similar request on existing issues (including closed ones).
+- [ ] I have read the [project progress](https://github.com/cotes2020/jekyll-theme-chirpy/projects) and know the current progress of the project.
+- [ ] I was in the `master` branch of the latest code.
 
 
-**Is your feature request related to a problem? Please describe.**
+# Is your feature request related to a problem? Please describe
 <!-- A clear and concise description of what the problem is. Ex. I'm always frustrated when [...] -->
 
-**Describe the solution you'd like**
+
+# Describe the solution you'd like
 <!-- A clear and concise description of what you want to happen. -->
 
-**Describe alternatives you've considered**
+
+# Describe alternatives you've considered
 <!-- A clear and concise description of any alternative solutions or features you've considered. -->
 
 
-**Additional context**
+# Additional context
 <!-- Add any other context or screenshots about the feature request here. -->