Add usage instructions

README.md

@@ -4,6 +4,24 @@ A library to read compiled, binary terminfo descriptions.
 
 _[![TermInfo NuGet Version](https://img.shields.io/nuget/v/TermInfo.svg?style=flat&label=NuGet%3A%20TermInfo)](https://www.nuget.org/packages/TermInfo)_
 
+## Usage
+
+```csharp
+// Load the active terminfo description
+var info = TermInfoDesc.Load();
+
+// Load via terminfo name
+var info = TermInfoDesc.Load("xterm-256color");
+
+// Default capabilities are strongly typed
+Debug.Assert(info.MaxColors == 256)
+
+// But extended capabilities are also supported
+bool? ax = info.Extended.GetBoolean("AX");
+int? u8 = info.Extended.GetNum("U8");
+string? kup = info.Extended.GetNum("kUP");
+```
+
 ## Building
 
 We're using [Cake](https://github.com/cake-build/cake) as a