chore: update src/library/module.cpp after update stage0

Co-authored-by: Eric Wieser <wieser.eric@gmail.com>

Update src/library/module.cpp

Co-authored-by: Eric Wieser <wieser.eric@gmail.com>

src/library/module.cpp

@@ -52,15 +52,16 @@ struct olean_header {
     // 1 byte: version, incremented on structural changes to header
     uint8_t version = 2;
     // 1 byte of flags:
-    // - whether persisted bignums use GMP or Lean-native encoding
+    // * bit 0: whether persisted bignums use GMP or Lean-native encoding
+    // * bit 1-7: reserved
     uint8_t flags =
 #ifdef LEAN_USE_GMP
         0b1;
 #else
         0b0;
 #endif
     // 33 bytes: Lean version string, padded with '\0' to the right
-    // e.g. "4.12.0-nightly-2024-10-18"
+    // e.g. "4.12.0-nightly-2024-10-18". May not be null-terminated.
     char lean_version[33];
     // 81b008650766442a0dfa9faa796e4588c9d7d3a1
     // 40 bytes: build githash, padded with `\0` to the right