Namespace hides `System.Console`.

[David-Rushton]

There are three issues with the current namespaces:

1. We hide System.Console

using System;

namespace Markdown.Console;

// Markdown.Console hides System.Console leading to...
System.Console.WriteLine("some text");

2. Current namespaces are not idiomatic

See #6 .

3. Using statements for calling apps are a little cluttered/repetitive

using Markdown.Console;

// Common
MarkdownConsole.Write("some markdown");

// Full qualified 
Markdown.Console.MarkdownConsole.Write("some markdown");

[David-Rushton]

Addressed in #8