message: Update comment for Ithaca operations
diff: //! Operation contents. This is the contents of the opaque field [super::operation::Operation::data].
  //!
  -//! Comparing to the previous protocol, new operation [`RegisterGlobalConstant`] has been added.
  -//! See http://tezos.gitlab.io/protocols/011_hangzhou.html#global-constants.
  +//! Changes comparing to the [`proto_011::operation::Operation`](crate::proto_011::operation::Operation):
  +//!
  +//!
  +//! - Removed `Operation::Endorsement`
  +//! - Removed `Operation::EndorsementWithSlot`
  +//! - Added `Operation::Preendorsement`
  +//! - Added `operation::Operation::Endorsement`
  +//! - Added `Operation::DoublePreendorsementEvidence`
  +//! - Modified `Operation::DoubleBakingEvidence`
  +//! - Modified `Operation::DoubleEndorsementEvidence`
  +//! - Added `Operation::SetDepositsLimit`
  pub use super::super::proto_011::operation::{
  ActivateAccountOperation, BallotOperation, ContractId, DelegationOperation,
  