docs: fix inaccurate UNIXTIME decode comment about Go behavior

The comment incorrectly said the raw int64 return matches "Go's
getInt64() behavior". Go's Rows.Next() actually converts UNIXTIME to
time.Time, not raw int64. The Python choice to return raw int64 is
correct for a wire protocol library, but the justification was wrong.

Closes #109

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: antoineleclair

src/dqlitewire/types.py

@@ -281,9 +281,12 @@ def decode_value(data: bytes, value_type: ValueType) -> tuple[Any, int]:
     elif value_type == ValueType.INTEGER:
         return decode_int64(data), 8
     elif value_type == ValueType.UNIXTIME:
-        # Return raw int64 to match Go's getInt64() behavior and preserve
-        # round-trip identity. Previously returned datetime.datetime, which
-        # caused type-changing re-encode (UNIXTIME → ISO8601).
+        # Return raw int64 to preserve round-trip identity at the wire level.
+        # Previously returned datetime.datetime, which caused type-changing
+        # re-encode (UNIXTIME → ISO8601). See issue 006.
+        # Note: Go's Rows.Next() converts this to time.Time, but that
+        # conversion belongs in a higher-level client layer, not the wire
+        # protocol codec.
         return decode_int64(data), 8
     elif value_type == ValueType.FLOAT:
         return decode_double(data), 8