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

docs/input/cli/commandApp.md

@@ -1,6 +1,9 @@
 Title: CommandApp
 Order: 2
 Description: "**CommandApp** is the entry point for a *Spectre.Console.Cli* command line application. It is used to configure the settings and commands used for execution of the application."
+Reference:
+    - T:Spectre.Console.Cli.CommandApp
+    - T:Spectre.Console.Cli.CommandApp`1
 ---
 
 `CommandApp` is the entry point for a `Spectre.Console.Cli` command line application. It is used to configure the settings and commands used for execution of the application. Most `Spectre.Console.Cli` applications will need to specify a custom configuration using the `Configure` method.

docs/input/cli/commands.md

@@ -1,9 +1,12 @@
 Title: Creating Commands
 Order: 6
 Description: "How to create commands for *Spectre.Console.Cli*"
+Reference:
+    - T:Spectre.Console.Cli.AsyncCommand`1
+    - T:Spectre.Console.Cli.Command`1
 ---
 
-Commands in `Spectre.Console.Cli` are defined by creating a class that inherits from either `Spectre.Console.Cli.Command<TSettings>` or `Spectre.Console.Cli.AsyncCommand<TSettings>`. `Command<TSettings>` must implement an `Execute` method that returns an int where as `AsyncCommand<TSettings>` must implement `ExecuteAsync`  returning `Task<int>`.
+Commands in `Spectre.Console.Cli` are defined by creating a class that inherits from either `Command<TSettings>` or `AsyncCommand<TSettings>`. `Command<TSettings>` must implement an `Execute` method that returns an int where as `AsyncCommand<TSettings>` must implement `ExecuteAsync`  returning `Task<int>`.
 
 ```csharp
 public class HelloCommand : Command<HelloCommand.Settings>

docs/input/cli/settings.md

@@ -1,6 +1,10 @@
 Title: Specifying Settings
 Order: 5
 Description: "How to define command line argument settings for your *Spectre.Console.Cli* Commands"
+Reference: 
+    - T:Spectre.Console.Cli.CommandSettings
+    - T:Spectre.Console.Cli.CommandArgumentAttribute
+    - T:Spectre.Console.Cli.CommandOptionAttribute
 ---
 
 Settings for `Spectre.Console.Cli` commands are defined via classes that inherit from `CommandSettings`. Attributes are used to indicate how the parser interprets the command line arguments and create a runtime instance of the settings to be used.