Merge pull request #6095 from haskell/phadej-bug-report-template

Update issue template

.github/ISSUE_TEMPLATE/bug_report.md

+---
+name: Bug report
+about: Create a report to help us improve
+title: ''
+labels: ''
+assignees: ''
+
+---
+
+**Describe the bug**
+A clear and concise description of what the bug is.
+
+**To Reproduce**
+Steps to reproduce the behavior:
+
+```
+$ cabal v2-build ...
+```
+
+Please use version-prefixed commands (e.g. `v2-build` or `v1-build`) to avoid ambiguity.
+
+**Expected behavior**
+A clear and concise description of what you expected to happen.
+
+**System informataion**
+ - Operating system
+ - `cabal`, `ghc` versions
+
+**Additional context**
+Add any other context about the problem here.