Add short summary at the top of issue template (#3799)

Author: max-sixty

.github/ISSUE_TEMPLATE/bug_report.md

@@ -7,6 +7,9 @@ assignees: ''
 
 ---
 
+<!-- A short summary of the issue, if appropriate -->
+
+
 #### MCVE Code Sample
 <!-- In order for the maintainers to efficiently understand and prioritize issues, we ask you post a "Minimal, Complete and Verifiable Example" (MCVE): http://matthewrocklin.com/blog/work/2018/02/28/minimal-bug-reports -->