add links (#187)

Author: Arhell

mkdocs.yml

@@ -238,3 +238,5 @@ nav:
           - Helper: support-helper.md
           - Registry: support-registry.md
           - Version: support-version.md
+  - Discussions: https://github.com/orgs/phalcon/discussions
+  - Blog: https://blog.phalcon.io/