added issue template (#245)

.github/ISSUE_TEMPLATE/bug_report.md

+---
+name: 🐛 Bug Report
+about: If something isn't working as expected 🤔.
+
+---
+
+## Bug Report
+
+### Current behavior
+<!-- A clear and concise description of the behavior. -->
+
+### Expected behavior
+<!-- A clear and concise description of what you expected to happen. -->
+
+### Environment
+
+- CLI version (output of `ardunio-cli version`):
+- Go version (if building from sources):
+- OS version:
+
+### Additional context
+<!-- (Optional) Add any other context about the problem here. -->
\ No newline at end of file