Create bug-report.md (#845)

.github/ISSUE_TEMPLATE/bug-report.md

+---
+name: Bug report
+about: Use this template to create a new bug report
+title: General problem description
+labels: 'bug'
+assignees: ''
+---
+
+#### Summary
+<!-- Explain what happened -->
+
+#### Steps to reproduce
+<!-- Give as thorough description as possible on how to reproduce the problem.
+If you can't remember the exact actions you took please try to give an accurate
+account of what happened and disclose any possible piece of information related to the problem. -->
+
+#### Expected behavior
+<!-- How did you expect the application to behave -->
+
+#### Actual behavior
+<!-- How did the application behave -->
+
+<!-- Extras: If the problem involves a specific file, providing that file would be helpful; screenshots are welcome too -->