Add Spiral to Micro frameworks

README.md

   - [Content Management Systems](#content-management-systems-cms)
   - [Components](#components)
   - [Micro Frameworks](#micro-frameworks)
+- [Spiral](https://github.com/spiral/framework) - Long-running PHP framework with RoadRunner application server.
   - [Micro Framework Extras](#micro-framework-extras)
   - [Routers](#routers)
   - [Templating](#templating)