Add a template for issues

.github/ISSUE_TEMPLATE.md

@@ -0,0 +1,18 @@
+### Before posting
+
+Please follow the steps below and check the boxes with [x] once you did the step.
+
+- [ ] I checked the issue tracker for similar issues
+- [ ] I checked the [changelog](https://github.com/clementine-player/Clementine/blob/master/Changelog) if the issue is already resolved
+- [ ] I tried the latest Clementine build from [here](https://builds.clementine-player.org/)
+
+### System information
+
+Please provide information about your system and the version of Clementine used.
+
+- Operating System:
+- Clementine version: 
+
+### Expected behaviour / actual behaviour
+
+### Steps to reproduce the problem (only for bugs)