Getting Started walkthrough for Remote Repositories

[joyceerhl]

Today vscode.dev has several walkthroughs, none of which are actually specific to vscode.dev. For users who are familiar with VS Code but land in vscode.dev from our website or a search engine and want to know how VS Code for the web differs from VS Code desktop, we should provide walkthroughs for the routes built into vscode.dev. This is a good opportunity to explain what you can and cannot do with Remote Repositories, for example. Here's a mockup of what this could look like: