chore(github): Update issue template to use external main che repository

Change-Id: Ia8b35492add6295ee58a94bd8bd1f0dd4bdde30d
Signed-off-by: Florent Benoit <[email protected]>

Author: benoitf

.github/ISSUE_TEMPLATE.md

@@ -0,0 +1,16 @@
+---
+name: "⚠️ Where to report issues?"
+about: File issues in the main Eclipse Che repository at https://github.com/eclipse/che/issues
+title: Issues need to be filed in the main Eclipse Che repository
+labels: ''
+assignees: ''
+
+---
+
+## Where to report issues?
+
+This repository is not the primary repository of Eclipse Che.
+
+🚨 Please don't submit new issues here. 🚨
+
+All issues for Eclipse Che are managed at [https://github.com/eclipse/che/issues](https://github.com/eclipse/che/issues).