Update README.md

Author: linquize

README.md

@@ -36,20 +36,21 @@ You are recommended to use our GUI program to manipulate the project file.
 It allows you to initialize the project with ProtoBuf MSBuild targets and properties.
 It automatically selects the required build action when adding new `.proto` files.
 
-1. Copy `ProtoBuf.MSBuildTask.dll` and `ProtoBuf.MSBuildTask.targets` to the directory of ProtoGen binaries.
-   Currently, we require the `ProtoBuf.MSBuildTask` files to be in the directory of ProtoGen binaries.
+1. Copy `ProtoBuf.MSBuildTask.dll` and `ProtoBuf.MSBuildTask.targets` to your project in a separate directory.
 2. Launch `ProtoBuf.ProjectInserter.WinForms` program.
 3. Open project, pick the C# project you wish to enable `ProtoBuf.MSBuildTask`.
-4. Initialize project, pick the directory to ProtoGen binaries.
-   Please put ProtoGen binaries in a location that is reachable from your repository.
-   **Relative path** of the directory to ProtoGen binaries is saved to the project file.
-   If ProtoGen binaries are located in another drive, **Absolute** path is saved.
-5. Add files, pick one or more files to add.
+4. Initialize project, pick the directories to `ProtoBuf.MSBuildTask` and `ProtoGen` binaries respectively.
+   Please put `ProtoBuf.MSBuildTask` files and `ProtoGen` binaries in locations that are reachable from your repository.
+   **Relative path** of the directories to these files are saved to the project file.
+   If these files are located in another drive, **Absolute** path will be saved.
+5. Add ProtoBuf files, pick one or more files to add.
 6. Save project.
 
 If you wish to manually add new `.proto` files to the project in Visual Studio or SharpDevelop,
 remember to select `Build Action`: `ProtoBuf` and enter `Custom Tool`: `MSBuild:Compile`.
 
+Note: Protocol files must reside in project directory or its subdirectories. `ProtoGen` does not support upper level such as `..\x.proto`.
+
 How to Contribute?
 --------------------
 Development happens on github. You are welcome to open pull requests or file issues.