Shorten issue template

Author: TentativeConvert

.github/ISSUE_TEMPLATE/lean4game-issues-and-feature-requests.md

@@ -0,0 +1,10 @@
+---
+name: Software bugs and features
+about: Raise issues regarding the software powering the Lean Game Server
+title: ''
+labels: ''
+assignees: ''
+
+---
+
+Please use this form only to report issues regarding the lean4game software, not regarding contents of individual games.  It may be worth checking first whether the bug you want to report or the feature you'd like to request is still/already present in the [development version](https://adam-dev.math.hhu.de/) of lean4game. In case of a server outage, please also <a href="mailto:adam@math.hhu.de?subject=Server Outage">email us</a>.