Describe features in README

api/README.md

@@ -9,3 +9,13 @@ Sign and verify `.zip` and `.tar.gz` files with an ed25519 signing key.
 This library contains the brains of [`zipsign`](https://github.com/Kijewski/zipsign).
 You can use it in your projects to verify and sign `.zip` and `.tar.gz` files
 without running a separate application, e.g. to verify a self-update.
+
+### Features
+
+* `default`: sign and verify `.tar.gz` and `.zip` files
+* `sign-tar`: sign a `.tar.gz` file
+* `verify-tar`: verify a signed `.tar.gz` file
+* `sign-zip`: sign a `.zip` file
+* `verify-zip`: verify a signed `.zip` file
+* `tar`: combines `sign-tar` and `verify-tar`
+* `zip`: combines `sign-zip` and `verify-zip`