github: permits blank issue

Blank issue might be used by devs to create tracking issue or by
advanced user to report more strange issue.

These kind of issue won't be parsed and won't be tagged. Normally bBug
report should be used for 99% of the cases.

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

.github/ISSUE_TEMPLATE/config.yml

@@ -1,5 +1,5 @@
 ---
-blank_issues_enabled: false
+blank_issues_enabled: true
 contact_links:
   - name: Feature request
     url: https://forum.openwrt.org/c/feature-requests