Document desktop deployment technologies such as ClickOnce for .NET 5

This issue will track the docs plan for creating an area in the guide related to deploying .NET 5 windows desktop apps. This is outside of a specific client technology such as WPF or WinForms. The content should be written as a tutorial ([how to write a tutorial](https://review.docs.microsoft.com/en-us/help/contribute/contribute-how-to-mvc-tutorial?branch=master) / [file template](https://review.docs.microsoft.com/en-us/help/contribute/global-tutorial-template?branch=master))

### General information

- [.NET Deployment Tools repo](https://github.com/dotnet/deployment-tools/)

#### ClickOnce

- [.NET 5 ClickOnce spec](https://github.com/dotnet/deployment-tools/issues/9)
- [.NET 5 RC2 Blog post detailing info about ClickOnce](https://devblogs.microsoft.com/dotnet/announcing-net-5-0-rc-2/#clickonce)

### Outline

01. Introduction
01. Why it's beneficial
01. Alternatives such as VS
01. Differences from .NET Fx ClickOnce
01. Contribution guide linked to ClickOnce GitHub
01. Install mage global tool
01. Publish
01. Note security concerns
01. Deploy
01. Install
01. Update
01. Installer project
01. Samples and walkthroughs
01. Troubleshooting
01. Launcher update availability diagnostics
01. Mage reference (link to cli docs)

### Potential article placement

It's possible that the file could be written once and shared between different TOCs.

#### WPF

**Repo file:** [https://github.com/dotnet/docs-desktop/tree/master/dotnet-desktop-guide/net/wpf/publish/clickonce.md](https://github.com/dotnet/docs-desktop/new/master/dotnet-desktop-guide/net/wpf/publish/)
**TOC location:**
- Windows Presentation Foundation for .NET
- Get started
- ...
- Migration
- ...
- Fundamentals
- ...
- Work with data
- ...
- **Publish with ClickOnce**

#### WinForms

**Repo file:** [https://github.com/dotnet/docs-desktop/tree/master/dotnet-desktop-guide/net/winforms/publish/clickonce.md](https://github.com/dotnet/docs-desktop/new/master/dotnet-desktop-guide/winforms/wpf/publish/)
**TOC location:**
- Windows Forms for .NET
- What's New
- Get started
- ...
- Migration
- ...
- Forms
- ...
- Controls
- ...
- User input - keyboard
- ...
- User input - mouse
- ...
- **Publish with ClickOnce**