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/players.ksy

@@ -0,0 +1,48 @@
+meta:
+  id: players
+  title: Players Save File
+  application: LEGO Island
+  file-extension: gsi
+  license: CC0-1.0
+  endian: le
+doc: |
+  Player profile save data for LEGO Island (1997). Stores up to 9 player
+  profiles, each identified by a 7-character username. Usernames are stored
+  as letter indices rather than ASCII characters.
+
+  The file is located at `<save_path>/Players.gsi` where save_path is
+  typically the game's installation directory.
+
+seq:
+  - id: count
+    type: s2
+    doc: |
+      Number of saved player profiles. The game supports a maximum of 9
+      players; when a 10th player is added, the oldest profile is deleted.
+  - id: entries
+    type: username
+    repeat: expr
+    repeat-expr: count
+    doc: Array of player username entries, ordered by most recently played.
+
+types:
+  username:
+    doc: |
+      A player username consisting of up to 7 letters. Each letter is stored
+      as a signed 16-bit index. The struct is always 14 bytes (0x0e).
+    seq:
+      - id: letters
+        type: s2
+        repeat: expr
+        repeat-expr: 7
+        doc: |
+          Letter indices for the username characters:
+          - 0-25: Standard alphabet (0=A, 1=B, ..., 25=Z)
+          - 29: International ä, å, or ñ (language-dependent)
+          - 30: International ö or æ (language-dependent)
+          - 31: International ß or ø (language-dependent)
+          - 32: International ü
+          - -1 (0xFFFF): Empty/unused position
+
+          Unused positions are filled with -1. A name shorter than 7
+          characters will have trailing -1 values.