Add GitHub issue templates

See gh-42770

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1,5 @@
+blank_issues_enabled: false
+contact_links:
+  - name: Asking for help
+    url: https://stackoverflow.com/tags/spring-boot
+    about: The Spring Boot team is using StackOverflow for general questions.

.github/ISSUE_TEMPLATE/issue.md

@@ -1,3 +1,11 @@
+---
+name: General
+about: Bugs, enhancements, documentation, tasks.
+title: ''
+labels: ''
+assignees: ''
+---
+
 <!--
 Thanks for raising a Spring Boot issue. Please take the time to review the following
 categories as some of them do not apply here.