add bug report template [skip ci]

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,25 @@
+---
+name: Bug report
+about: Meson bug report
+title: ''
+labels: ''
+assignees: ''
+
+---
+
+**Describe the bug**
+A clear and concise description of what the bug is.
+
+**To Reproduce**
+Please include your `meson.build` files, preferably as a minimal toy example showing the issue.
+You may need to create simple source code files (don't include private/proprietary code).
+
+**Expected behavior**
+A clear and concise description of what you expected to happen.
+
+**system parameters**
+* Is this a [cross build](https://mesonbuild.com/Cross-compilation.html) or just a plain native build (for the same computer)?
+* what operating system (e.g. MacOS Catalina, Windows 10, CentOS 8.0, Ubuntu 18.04, etc.)
+* what Python version are you using e.g. 3.8.0
+* what `meson --version`
+* what `ninja --version` if it's a Ninja build