github: add release info to BUG template

Add release info to BUG template. Having the reported release is an
additional info to better bisect the bug and what release is affected.

This is also useful in preparation for action that will parse BUG
template and add tag and do validations.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>

.github/ISSUE_TEMPLATE/bug-report.yml

@@ -19,6 +19,15 @@ body:
         ```. /etc/openwrt_release && echo $DISTRIB_REVISION```
     validations:
       required: true
+  - type: input
+    id: release
+    attributes:
+      label: OpenWrt release
+      description: |
+        The OpenWrt release or commit hash where this bug occurs (use command below).
+        ```. /etc/openwrt_release && echo $DISTRIB_RELEASE```
+    validations:
+      required: true
   - type: input
     id: target
     attributes: