Add issue template

Author: gdt

.github/issue-template.md

@@ -0,0 +1,12 @@
+# Instructions for using the issue tracker
+
+The issue tracker is not a help system.  Before using the issue
+tracker, please read the following page thoroughly and follow the
+guidelines it expresses:
+
+https://github.com/bcpierce00/unison/wiki/Reporting-Bugs-and-Feature-Requests
+
+Pleaes delete the following dashed line and the text above it, leaving the
+statement that you have read the wiki page.
+----------------------------------------
+I have thoroughly read the [Reporting Bugs and Feature Requests](https://github.com/bcpierce00/unison/wiki/Reporting-Bugs-and-Feature-Requests) wiki page.