chore: update issue template for bug

Author: anikethsaha

.github/ISSUE_TEMPLATE/bug_report.md

@@ -7,6 +7,7 @@ about: Create a report to help us improve
 <!-- Please use English language -->
 <!-- Before creating an issue please make sure you are using the latest version of Docsify. -->
 <!-- Please ask questions on StackOverflow: https://stackoverflow.com/questions/ask?tags=docsify -->
+<!-- Please ask questions on gitter: https://gitter.im/docsifyjs/Lobby -->
 
 ## Bug Report
 
@@ -36,3 +37,9 @@ about: Create a report to help us improve
 
 <!-- Love docsify? Please consider supporting our collective:
 👉  https://opencollective.com/docsify/donate -->
+
+#### Please create a reproducible sandbox 
+
+[![Edit 307qqv236](https://codesandbox.io/static/img/play-codesandbox.svg)](https://codesandbox.io/s/307qqv236)
+
+#### Mention the docsify version in which this bug was not present (if any)