Add initial Kaitai formats to document LEGO Island file formats (#1712)

* Add initial Kaitai formats

* Update README with installation and command examples

Added installation instructions for Kaitai Struct Visualizer and updated ksdump command examples.

* Update README.md

* Update link to Kaitai Struct documentation

* Update installation link for Kaitai Struct Visualizer

docs/README.md

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+# LEGO Island File Format Documentation
+
+This folder contains documentation for LEGO Island's custom binary file formats using [Kaitai Struct](https://kaitai.io/), a declarative language for describing binary data structures.
+
+## What is Kaitai Struct?
+
+Kaitai Struct allows you to define binary formats in a YAML-based `.ksy` file, which can then be:
+- Compiled into parser libraries for [many programming languages](https://kaitai.io/#quick-start) (C++, Python, JavaScript, etc.)
+- Visualized interactively using the [Kaitai Struct Visualizer](https://github.com/kaitai-io/kaitai_struct_visualizer)
+- Dumped to human-readable formats using `ksdump`
+
+<img width="1877" height="706" alt="image" src="https://github.com/user-attachments/assets/0d124219-1208-48ce-83bb-f433d9bb84b1" />
+
+## Documented Formats
+
+| File | Extension | Description |
+|------|-----------|-------------|
+| [`players.ksy`](/docs/players.ksy) | `.gsi` | Player profile save data (usernames) |
+| [`history.ksy`](/docs/history.ksy) | `.gsi` | Score history and high scores |
+
+## Using the Tools
+
+### Installation
+
+See the [Kaitai Struct Visualizer installation instructions](https://github.com/kaitai-io/kaitai_struct_visualizer?tab=readme-ov-file#downloading-and-installing) for setup details.
+
+### Kaitai Struct Visualizer (ksv)
+
+The [Kaitai Struct Visualizer](https://github.com/kaitai-io/kaitai_struct_visualizer) (`ksv`) provides an interactive terminal UI for exploring binary files.
+
+```bash
+# View a Players.gsi file
+ksv samples/Players.gsi players.ksy
+
+# View a History.gsi file
+ksv samples/History.gsi history.ksy
+```
+
+### Kaitai Struct Dump (ksdump)
+
+`ksdump` outputs the parsed structure as JSON or YAML for scripting and inspection.
+
+```bash
+# Dump Players.gsi to JSON
+ksdump --format json samples/Players.gsi players.ksy
+
+# Dump History.gsi to YAML
+ksdump --format yaml samples/History.gsi history.ksy
+```
+
+## Sample Files
+
+The [`samples/`](/docs/samples/) directory contains example save files for testing:
+- `Players.gsi` - Sample player profile data
+- `History.gsi` - Sample score history data