added notes to copy latest UnityFileSystemAPI and link to sdk 9 download

Author: xdegtyarev

README.md

@@ -7,15 +7,11 @@ content of Unity data files. You can directly jump
 if your goal is to understand how to use the UnityDataTool command-line tool.
 
 The UnityFileSystemApi library is distributed in the Tools folder of the Unity editor (starting in
-version 2022.1.0a14). For simplicity, it is also included in this repository. The library is
+version 2022.1.0a14). For simplicity, it is also included in this repository. The library is somewhat
 backward compatible, which means that it can read data files generated by any previous version of
-Unity.
-
-Note that the UnityFileSystemApi library included in this repository is a custom version containing
-an additional function that is required to support the
-[SerializeReference](https://docs.unity3d.com/ScriptReference/SerializeReference.html)
-attribute. This version of the library will be included in future releases of Unity.
-
+Unity. Ideally, you should copy UnityFileSystemApi (.dll/.dylib) from Unity Editor install path 
+`Data/Tools/` subfolder to `UnityDataTool/UnityFileSystem/` of an Engine version that produced
+serialized data you want to analyze.
 
 ## What is the purpose of the UnityFileSystemApi native library?
 
@@ -82,15 +78,18 @@ The repository contains the following items:
 
 ## How to build
 
-The projects in this solution require the .NET 9.0 SDK. You can use your favorite IDE to build them.
+The projects in this solution require the [.NET 9.0 SDK](https://dotnet.microsoft.com/en-us/download/dotnet/9.0). 
+You can use your favorite IDE to build them.
 They were tested in Visual Studio on Windows and Rider on Mac.
 
 It is also possible to build the projects from the CLI using this command:
 
 `dotnet build -c Release`
 
-## Disclaimer
+(Optional) Copying current editor `UnityFileSystemApi`(.so/.dll/.dylib) library from 
+`{UnityEditor Install Folder}/Data/Tools/` to `UnityDataTool/UnityFileSystem/` before building. 
 
+## Disclaimer
 This project is provided on an "as-is" basis and is not officially supported by Unity. It is an
 experimental tool provided as an example of what can be done using the UnityFileSystemApi. You can
 report bugs and submit pull requests, but there is no guarantee that they will be addressed.