Create ISSUE_TEMPLATE.md

A new issue template proposed to try and steer people towards #matrix:matrix.org for support queries relating to running their own homeserver.

ISSUE_TEMPLATE.md

+<!-- 
+
+**IF YOU HAVE SUPPORT QUESTIONS ABOUT RUNNING OR CONFIGURING YOUR OWN HOME SERVER**: 
+PLease don't file a bug; you will likely get better support more quickly if you 
+ask in #matrix:matrix.org ;)
+
+
+This is a bug report template. By following the instructions below and
+filling out the sections with your information, you will help the us to get all
+the necessary data to fix your issue.
+
+You can also preview your report before submitting it. You may remove sections
+that aren't relevant to your particular case.
+
+Text between <!-- and --​> marks will be invisible in the report.
+-->
+
+### Description
+
+Describe here the problem that you are experiencing, or the feature you are requesting.
+
+### Steps to reproduce
+
+- For bugs, list the steps
+- that reproduce the bug
+- using hyphens as bullet points
+
+Describe how what happens differs from what you expected.
+
+### Version information
+
+<!-- IMPORTANT: please answer the following questions, to help us narrow down the problem -->
+
+- **Homeserver**: was this issue identified on matrix.org or another homeserver?
+- **Platform**:   tell us about the environment in which your homeserver is operating
+                  - distro, hardware, if it's running in a vm/container, etc.