feat: ratings leaderboard disk format

docs/guide/bkrl.md

@@ -0,0 +1,50 @@
+# Blitzkrieg Ratings Leaderboard
+
+A straightforward way of storing the entire World of Tanks Blitz ratings leaderboard to disk.
+
+```cpp
+primary BlitzkriegRatingsLeaderboard {
+  utf8"BKRL" magic;
+  Header header;
+  primary Body<header> body;
+}
+
+Header {
+  uint16 version; // always 1
+  Format format;
+  uint32 count;
+}
+
+Format enum<uint8> {
+  Minimal,
+  Comprehensive1,
+}
+
+Body<Header header> match<header.format> {
+  Minimal {
+    primary {
+      uint32 id;
+      uint16 score;
+    }[header.count] entries;
+  };
+
+  Comprehensive1 {
+    primary {
+      uint32 id;
+      uint16 score;
+
+      uint32 battles;
+      uint32 wins;
+      uint32 survived;
+
+      uint32 damageDealt;
+      uint32 damageReceived;
+
+      uint32 shots;
+      uint32 hits;
+
+      uint32 kills;
+    }[header.count] entries;
+  };
+}
+```