Add a changelog

Author: natecook1000

CHANGELOG.md

@@ -0,0 +1,44 @@
+# CHANGELOG
+
+<!-- 
+Add new items at the end of the relevant section under **Unreleased**.
+-->
+
+This project follows semantic versioning. While still in major version `0`,
+source-stability is only guaranteed within minor versions (e.g. between
+`0.0.3` and `0.0.4`). If you want to guard against potentially source-breaking
+package updates, you can specify your package dependency using
+`.upToNextMinor(from: "0.0.1")` as the requirement.
+
+## [Unreleased]
+
+### Additions
+
+- The `EX_USAGE` exit code is now used for validation errors.
+- The parser provides near-miss suggestions when a user provides an unknown
+  option.
+- `ArgumentParser` now builds on Windows.
+- You can throw an `ExitCode` error to exit without printing any output.
+
+### Fixes
+
+- Cleaned up a wide variety of documentation typos and shortcomings.
+- Improved different kinds of error messages:
+  - Duplicate exclusive flags now show the duplicated arguments.
+  - Subcommand validation errors print the correct usage string.
+- In the help screen:
+  - Removed the extra space before the default value for arguments without
+    descriptions.
+  - Removed the default value note when the default value is an empty string.
+  - Default values are now shown for Boolean options.
+
+## [0.0.1] - 2020-02-27
+
+- `ArgumentParser` initial release.
+
+
+
+
+[Unreleased]: https://github.com/apple/swift-argument-parser/compare/0.0.1...HEAD
+[0.0.1]: https://github.com/apple/swift-argument-parser/releases/tag/0.0.1
+