Add docs for ANSI functionality

Spectre.Docs/Content/console/how-to/writing-ansi.md

@@ -0,0 +1,88 @@
+---
+title: "Write ANSI"
+description: "How to write ANSI/VT sequences and markup without the Spectre.Console library"
+uid: "write-ansi"
+order: 2180
+---
+
+As of version `0.54.1-alpha.0.33`, the Spectre.Console library relies on a library called
+`Spectre.Console.Ansi` to emit ANSI/VT escape sequences and
+[markup](xref:console-markup-reference) in the terminal.
+
+## Creating an AnsiWriter
+
+Create a new `AnsiWriter` that automatically detects capabilities.
+
+```csharp
+var writer = new AnsiWriter(Console.Out);
+```
+
+Create a new `AnsiWriter` with specific capabilities.  
+Useful for testing, but usually not recommended.
+
+```csharp
+var writer = new AnsiWriter(
+    Console.Out, 
+    new AnsiCapabilities 
+    {
+        Ansi = true,
+        Links = true,
+        ColorSystem = ColorSystem.TrueColor,
+        AlternateBuffer = true,
+    });
+```
+
+> [!CAUTION]
+> Creating an `AnsiWriter` can be expensive, so make sure that you cache
+> and reuse them between writes, especially when detecting capabilities.
+
+## Emitting ANSI
+
+To emit ANSI, you can either write "raw" ANSI/VT escape sequences directly
+or use the built-in fluent API.
+
+```csharp
+writer
+    .BeginLink("https://spectreconsole.net", linkId: 123)
+    .Decoration(Decoration.Bold | Decoration.Italic)
+    .Foreground(Color.Yellow)
+    .Write("Spectre Console")
+    .ResetStyle()
+    .EndLink();
+```
+
+## Emitting Markup
+
+You can also emit [markup](xref:console-markup-reference) using the `AnsiWriter`.
+
+```csharp
+writer.Markup(
+    "[yellow bold italic link=https://spectreconsole.net]" + 
+    "Spectre.Console[/]");
+```
+
+## System.Console Extensions
+
+If you're running .NET 10 with C# 14 enabled, you can use the
+new functionality directly from `System.Console`.
+
+```csharp
+using System;
+
+Console.Markup("[yellow]Hello[/] ");
+Console.MarkupLine("[blue]World[/]");
+
+Console.Ansi(writer => writer
+    .BeginLink("https://spectreconsole.net", linkId: 123)
+    .Decoration(Decoration.Bold | Decoration.Italic)
+    .Foreground(Color.Yellow)
+    .Write("Spectre Console")
+    .ResetStyle()
+    .EndLink());
+```
+
+## See Also
+
+- <xref:console-markup-reference> - Markup reference
+- <xref:console-color-reference> - All available color names
+- <xref:console-text-styles> - All decoration options (bold, italic, etc.)