Add GitHub issue template configuration to disable blank issues

This commit adds a config.yml file under .github/ISSUE_TEMPLATE to disable
blank issues and provide a contact link directing users to create Discussions
for feature requests, bug reports, or questions. This helps streamline issue
reporting and encourages community engagement through GitHub Discussions.

.github/ISSUE_TEMPLATE/config.yml

+blank_issues_enabled: false
+contact_links:
+  - name: Features, Bug Reports, Questions
+    url: https://github.com/krzyzanowskim/STTextView/discussions/new?category=general
+    about: Our preferred starting point if you have any questions or suggestions about configuration, features or behavior.