Add bug report template

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,32 @@
+---
+name: Bug report
+about: Create a report to help us improve
+---
+
+This issue tracker is **ONLY** used for reporting bugs. 
+
+Feature requests, questions, and other discussions should be posted in the
+[Discussions](https://github.com/quickstrom/quickstrom/discussions) forum.
+
+**Describe the bug**
+A clear and concise description of what the bug is.
+
+**To reproduce**
+Steps to reproduce the behavior:
+1. Go to '...'
+2. Click on '....'
+3. Scroll down to '....'
+4. See error
+
+**Expected behavior**
+A clear and concise description of what you expected to happen. Include
+screenshots, logs or stack traces if applicable.
+
+**Environment (please complete the following information):**
+ - OS: [e.g. Ubuntu 18.04, macOS 10.10]
+ - Quickstrom version or commit [e.g. 0.1.0]
+ - Browser and webdriver information: [e.g. Firefox 86.0 and Geckodriver 0.29.1]
+ - Build environment or installation method [e.g. Nix, Cabal, Docker]
+
+**Additional context**
+Add any other context about the problem here.