Add GitHub issue template with info about support requests

.github/ISSUE_TEMPLATE.md

@@ -0,0 +1,37 @@
+<!--
+   SUPPORT REQUESTS: This is for reporting bugs in Mempool.
+   If you have a support request, please join our Keybase group:
+   https://keybase.io/team/mempool
+-->
+
+### Description
+
+<!-- brief description of the bug -->
+
+#### Version
+
+<!-- commit id or version number -->
+
+### Steps to reproduce
+
+<!--if you can reliably reproduce the bug, list the steps here  -->
+
+### Expected behaviour
+
+<!--description of the expected behavior -->
+
+### Actual behaviour
+
+<!-- explain what happened instead of the expected behaviour -->
+
+### Screenshots
+
+<!--Screenshots if gui related, drag and drop to add to the issue -->
+
+#### Device or machine
+
+<!-- device/machine used, operating system -->
+
+#### Additional info
+
+<!-- Additional information useful for debugging (e.g. logs) -->