Update issue templates

Author: valentine195

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,17 @@
+---
+name: Bug report
+about: Create a report to help me improve the plugin
+title: ''
+labels: bug
+assignees: ''
+
+---
+
+**Describe the bug**
+A clear and concise description of what the bug is.
+
+**Markdown Source**
+The markdown source that caused the rendering issue.
+
+**Screenshots**
+If applicable, add screenshots to help explain your problem.