message: doc: fix counter to Rust type mapping
diff: | float | f32 | all |
  | double | f64 | all |
  | uuid | [Uuid](https://doc.rust-lang.org/uuid/uuid/struct.Uuid.html) | all |
  -| counter | u64 | all |
  +| counter | i64 | all |
  #### complex types
  | Cassandra | Rust + CDRS |
  