Updates User Guide section of swift-java README.md. (#935)

Author: davelester

README.md

@@ -220,24 +220,20 @@ Please read the documentation of both performance testing tools, and note that r
 
 ## User Guide
 
-More details about the project can be found in [docc](https://www.swift.org/documentation/docc/) documentation.
+The swift-java project's [documentation](https://swiftpackageindex.com/swiftlang/swift-java/main/documentation/swiftjavadocumentation) is available on the Swift Package Index.
 
-To view the rendered docc documentation you can use the docc preview command:
+To preview the [DocC](https://www.swift.org/documentation/docc/) documentation, run:
 
 ```bash
+# macOS
 xcrun docc preview Sources/SwiftJavaDocumentation/Documentation.docc
 
-# OR SwiftJava to view SwiftJava documentation:
-# xcrun docc preview Sources/SwiftJava/Documentation.docc
-
-# ========================================
-# Starting Local Preview Server
-#	 Address: http://localhost:8080/documentation/documentation
-# ========================================
-# Monitoring /Users/ktoso/code/swift-java/Sources/SwiftJavaDocumentation/Documentation.docc for changes...
-
+# Linux (or any setup where docc is on your PATH)
+docc preview Sources/SwiftJavaDocumentation/Documentation.docc
 ```
 
+To preview the `SwiftJava` documentation instead, use `Sources/SwiftJava/Documentation.docc` as the path.
+
 ## Project Status
 
 **This project is under active development. We welcome feedback about any issues you encounter.**