Add issue templates

.github/ISSUE_TEMPLATE.md

+**Do you want to request a *feature* or report a *bug*?**
+
+**What is the current behavior?**
+
+**If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem.**
+
+**What is the expected behavior?**
+
+**Did this work in previous versions of DocumentServer?**
+
+**DocumentServer Docker tag:**
+
+**Host Operating System:**