.github: Add minimal issue template

Closes #11042

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,30 @@
+---
+name: Bug report
+about: For bugs and general problems
+title:
+labels: ''
+assignees: ''
+
+---
+
+Cockpit version: xxx
+OS:
+Page: <!--- If applicable, for instance "Network", "Machines", etc... -->
+
+<!--- Issue description -->
+
+<!---
+Please help us out by explaining how to reproduce it.
+
+Relevant parts of the system log are also useful:
+`journalctl --since -10m` if the issue happened in the last 10 minutes
+`journalctl -u cockpit -u <unit>` if you know which unit it concerns
+-->
+
+Steps to reproduce
+
+1.
+2.
+3.
+
+<!--- In case the issue is clearly visible, screenshots are very helpful -->

.github/ISSUE_TEMPLATE/enhancement.md

@@ -0,0 +1,12 @@
+---
+name: Enhancement
+about: For feature requests and discussion of ideas
+title:
+labels: 'enhancement'
+assignees: ''
+
+---
+
+Page: <!--- If applicable, for instance "Network", "Machines", etc... -->
+
+<!--- Feature description -->