Add issue template for better orientation

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1,11 @@
+blank_issues_enabled: false
+contact_links:
+  - name: Report a security vulnerability
+    url: https://reactphp.org/#support
+    about: 'If you discover a security vulnerability, please send us an email. Do not disclose security-related Issues publicly.'
+  - name: Feature request
+    url: https://github.com/orgs/reactphp/discussions/categories/ideas
+    about: 'You have ideas to improve our project? Start a new discussion in our "ideas" category.'
+  - name: Questions
+    url: https://github.com/orgs/reactphp/discussions/categories/q-a
+    about: 'We are happy to answer your questions! Start a new discussion in our "Q&A" category.'