docs(project): add issue template

.github/ISSUE_TEMPLATE.md

@@ -0,0 +1,16 @@
+<!--
+
+Make sure to checkout [CONTRIBUTING.md](https://github.com/bpmn-io/bpmn-js/blob/master/CONTRIBUTING.md#creating-an-issue) before filing a bug or feature request.
+
+If possible, reproduce bugs through a [JSFiddle snippet](https://jsfiddle.net/kxqy09gf) or in a separate project on GitHub.
+
+-->
+
+
+### Expected Behavior
+
+
+### Actual Behavior
+
+
+### Steps to reproduce the Behavior