Add issue template

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,35 @@
+---
+name: Bug report
+about: Create a report to help us improve
+title: ''
+labels: bug
+assignees: ''
+
+---
+
+**Describe the bug**
+A clear and concise description of what the bug is.
+
+**NPCLib usage option**
+NPCLib can be used in multiple ways, please provide [the number](https://github.com/JitseB/NPCLib#usage) corresponding to your usage option.
+
+**NPCLib JAR name**
+E.g. npclib-plugin-2.0.1-SNAPSHOT.jar
+
+**Server version**
+E.g. CraftBukkit version git-Spigot-a1f2566-97b0057 (MC: 1.13.2) (Implementing API version 1.13.2-R0.1-SNAPSHOT) (use command `/version`)
+
+**To Reproduce**
+Steps to reproduce the behavior:
+- Used code  '...'
+- Actions in game '....'
+- See error '....'
+
+**Expected behavior**
+A clear and concise description of what you expected to happen.
+
+**Screenshots**
+If applicable, add screenshots to help explain your problem.
+
+**Additional context**
+Add any other context about the problem here.