Add template for "regular" issue

.github/ISSUE_TEMPLATE.md

@@ -1 +1,27 @@
-Test
+<!--
+
+Welcome! If you have a question or are unsure if you should open an issue,
+please use the forum instead!
+
+   https://forum.restic.net
+
+The forum is a better place for questions about restic or general suggestions
+and topics, e.g. usage or documentation questions! This issue tracker is mainly
+for tracking bugs and feature requests directly relating to the development of
+the software itself, rather than the project.
+
+Thanks for understanding, and for contributing to the project!
+-->
+
+
+Output of `restic version`
+--------------------------
+
+<!--
+Please add the version of restic you're currently using here, this helps us
+later to see what has changed in restic when we revisit this issue after some
+time.
+-->
+
+Describe the issue
+------------------