Add key features #419

{
  "key_features": [
    {
      "icon": "features-oop",
      "title": "Modern",
      "content": "C# is a modern, fast-evolving language."
    },
    {
      "icon": "features-strongly-typed",
      "title": "Cross-platform",
      "content": "C# runs on almost any platform and chipset."
    },
    {
      "icon": "features-functional",
      "title": "Multi-paradigm",
      "content": "C# is primarily an object-oriented language, but also has lots of functional features."
    },
    {
      "icon": "features-lazy",
      "title": "General purpose",
      "content": "C# can be used for a wide variety of workloads, like websites, console applications, and even games."
    },
    {
      "icon": "features-declarative",
      "title": "Tooling",
      "content": "C# has excellent tooling, with linting and advanced refactoring options built-in."
    },
    {
      "icon": "features-generic",
      "title": "Documentation",
      "content": "Documentation is excellent and exhaustive, making it easy to get started with C#."
    }
  ]
}