github: add issue templates

cgroups-rs should not use the repository default issue templates.
Let's add a private version to override the default ones.

Fixes: #29
Signed-off-by: Peng Tao <bergwolf@hyper.sh>

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,17 @@
+---
+name: Bug report
+about: Create a report to help us improve
+title: ''
+labels: 'bug, needs-review'
+assignees: ''
+
+---
+
+**Describe the bug**
+A clear and concise description of what the bug is.
+
+**Expected behavior**
+A clear and concise description of what you expected to happen.
+
+**Additional context**
+Add any other context about the problem here.