config: issue template chooser customization

https://docs.github.com/en/communities/using-templates-to-encourage-useful-issues-and-pull-requests/configuring-issue-templates-for-your-repository#configuring-the-template-chooser

Author: fpistm

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1,8 @@
+blank_issues_enabled: false
+contact_links:
+  - name: Ask a question
+    about: For general-purpose questions and answers, see the Discussions section.
+    url: https://github.com/stm32duino/Arduino_Core_STM32/discussions
+  - name: Request support
+    about: Please check out the Arduino for STM32 forum.
+    url: https://www.stm32duino.com/