Migrate documentation for Usage to DocC #8593
Description
Description
In an effort to create a consolidated single source for the swift package manager documentation, this issue will track the work to be done in moving the contents of Usage.md into our DocC catalogue.
Each of the top level section headings in Usage.md maps pretty effectively to its own article:
* [Creating a Package](#creating-a-package)
* [Creating a Library Package](#creating-a-library-package)
* [Creating an Executable Package](#creating-an-executable-package)
* [Creating a Macro Package](#creating-a-macro-package)
* [Defining Dependencies](#defining-dependencies)
* [Publishing a Package](#publishing-a-package)
* [Requiring System Libraries](#requiring-system-libraries)
* [Packaging Legacy Code](#packaging-legacy-code)
* [Handling Version-specific Logic](#handling-version-specific-logic)
* [Editing a Package](#editing-a-package)
* [Top of Tree Development](#top-of-tree-development)
* [Resolving Versions (Package.resolved file)](#resolving-versions-packageresolved-file)
* [Setting the Swift Tools Version](#setting-the-swift-tools-version)
* [Testing](#testing)
* [Running](#running)
* [Setting the Build Configuration](#setting-the-build-configuration)
* [Debug](#debug)
* [Release](#release)
* [Additional Flags](#additional-flags)
* [Depending on Apple Modules](#depending-on-apple-modules)
* [Creating C Language Targets](#creating-c-language-targets)
* [Using Shell Completion Scripts](#using-shell-completion-scripts)
The first step of this is directly porting - and not updating - the content for these topics, creating loosely 12-14 short articles.