Add issue template

.github/ISSUE_TEMPLATE.md

@@ -0,0 +1,33 @@
+**Notice (you can delete this paragraph)**
+
+Please understand that we use GitHub as **bug tracker and for feature requests only**.
+
+For general (community) support and other discussion, you are welcome to visit us @ Freenode, #mailcow
+
+Answering may take from a few seconds to hours, please be patient. :-)
+
+Immediate commercial support is available via mailcow@incidents.servercow.de
+
+**Describe the bug**
+A clear and concise description of what the bug is.
+
+**To Reproduce**
+Steps to reproduce the behavior:
+1. Go to '...'
+2. Click on '....'
+3. Scroll down to '....'
+4. See error
+
+**Expected behavior**
+A clear and concise description of what you expected to happen.
+
+**Screenshots**
+If applicable, add screenshots to help explain your problem.
+
+**System**
+ - OS: [e.g. iOS]
+ - Browser: [e.g. chrome, safari]
+ - Other clients involved:
+
+**Additional context**
+Add any other context about the problem here.