Add links to the docs to the README (#396)

* Add links to docs to the README

* Light article revisions

Author: natecook1000

.gitignore

@@ -3,4 +3,5 @@
 /Packages
 /*.xcodeproj
 .swiftpm
+.vscode
 .*.sw?

README.md

@@ -66,10 +66,18 @@ OPTIONS:
   -h, --help              Show help for this command.
 ```
 
-For more information and documentation about all supported options, 
-see the library's documentation in Xcode.
+## Documentation
 
-## Examples
+For guides, articles, and API documentation see the 
+[library's documentation on the Web][docs] or in Xcode.
+
+- [ArgumentParser documentation][docs]
+- [Getting Started with ArgumentParser](https://apple.github.io/swift-argument-parser/documentation/argumentparser/gettingstarted)
+- [`ParsableCommand` documentation](https://apple.github.io/swift-argument-parser/documentation/argumentparser/parsablecommand)
+
+[docs]: https://apple.github.io/swift-argument-parser/documentation/argumentparser/
+
+#### Examples
 
 This repository includes a few examples of using the library:
 
@@ -79,8 +87,8 @@ This repository includes a few examples of using the library:
 
 You can also see examples of `ArgumentParser` adoption among Swift project tools:
 
-- [`indexstore-db`](https://github.com/apple/indexstore-db/pull/72) is a simple utility with two commands.
-- [`swift-format`](https://github.com/apple/swift-format/pull/154) uses some advanced features, like custom option values and hidden flags.
+- [`swift-format`](https://github.com/apple/swift-format/) uses some advanced features, like custom option values and hidden flags.
+- [`swift-package-manager`](https://github.com/apple/swift-package-manager/) includes a deep command hierarchy and extensive use of option groups.
 
 ## Project Status
 

Sources/ArgumentParser/Documentation.docc/Articles/ExperimentalFeatures.md

@@ -1,11 +1,19 @@
 # Experimental Features
-Learn about what experimental features ArgumentParser has.
+
+Learn about ArgumentParser's experimental features.
 
 ## Overview
-ArgumentParser has some built-in experimental features and they are available with the prefix `--experimental`. If you have any feedback on the experimental features, please open an issue.
 
-## List of experimental features
-### Experimental Flags
+Command-line programs built using `ArgumentParser` may include some built-in experimental features, available with the prefix `--experimental`. These features should not be considered stable while still prefixed, as future releases may change their behavior or remove them.
+
+If you have any feedback on experimental features, please [open a GitHub issue][issue].
+
+## List of Experimental Features
+
 | Name | Description | related PRs | Version |
 | ------------- | ------------- | ------------- | ------------- |
-| `--experimental-dump-help`  | Dumps command/argument/help information as JSON | [#310](https://github.com/apple/swift-argument-parser/pull/310) [#335](https://github.com/apple/swift-argument-parser/pull/335) | 0.5.0 or newer |
+| `--experimental-dump-help`  | Dumps command/argument/help information as JSON | [#310][] [#335][] | 0.5.0 or newer |
+
+[#310]: https://github.com/apple/swift-argument-parser/pull/310
+[#335]: https://github.com/apple/swift-argument-parser/pull/335
+[issue]: https://github.com/apple/swift-argument-parser/issues/new/choose 

Sources/ArgumentParser/Documentation.docc/Articles/ManualParsing.md

@@ -1,10 +1,10 @@
 # Manual Parsing and Testing
 
-Provide your own array of command-line inputs and work with parsed results by calling alternatives to `main()`.
+Provide your own array of command-line inputs or work directly with parsed command-line arguments.
 
 ## Overview
 
-For most programs, calling the static `main()` method on the root command type is all that's necessary. That single call parses the command-line arguments to find the correct command from your tree of nested subcommands, instantiates and validates the result, and executes the chosen command. For more control, however, you can perform each of those steps manually.
+For most programs, denoting the root command type as `@main` is all that's necessary. As the program's entry point, that type parses the command-line arguments to find the correct command from your tree of nested subcommands, instantiates and validates the result, and executes the chosen command. For more control, however, you can perform each of those steps manually.
 
 ## Parsing Arguments