Docs redesign (#728)

* Adding a dark mode
* Adding reference for types to summary pages
* Adding API Reference
* Adding modifiers to methods/fields/etc
* Minimizing files input
* Caching a lot of the output pages
* Cache only for each execution
* Adding API references to existing docs

examples/Console/Progress/DescriptionGenerator.cs

@@ -1,7 +1,7 @@
 using System;
 using System.Collections.Generic;
 
-namespace Spectre.Console.Examples;
+namespace Progress;
 
 public static class DescriptionGenerator
 {

examples/Console/Progress/Program.cs

@@ -1,8 +1,9 @@
 using System;
 using System.Collections.Generic;
 using System.Threading;
+using Spectre.Console;
 
-namespace Spectre.Console.Examples;
+namespace Progress;
 
 public static class Program
 {