message: Document removal of StakingMsg::Withdraw in MIGRATING [skip ci]
diff: @@ -299,6 +299,30 @@ major releases of `cosmwasm`. Note that you can also view the
  and 28 bytes when its canonical representation is base64 encoded). For fixed
  length database keys `CanonicalAddr` remains handy though.
  +- Replace `StakingMsg::Withdraw` with `DistributionMsg::SetWithdrawAddress` and
  + `DistributionMsg::WithdrawDelegatorReward`. `StakingMsg::Withdraw` was a
  + shorthand for the two distribution messages. However, it was unintuitive
  + because it did not set the address for one withdraw only but for all following
  + withdrawls. Since withdrawls are [triggered by different
  + events][distribution docs] such as validators changing their commission rate,
  + an address that was set for a one-time withdrawl would be used for future
  + withdrawls not considered by the contract author.
  +
  + If the contract never set a withdraw address other than the contract itself
  + (`env.contract.address`), you can simply replace `StakingMsg::Withdraw` with
  + `DistributionMsg::WithdrawDelegatorReward`. It is then never changed from the
  + default. Otherwise you need to carefully track what the current withdraw
  + address is. A one-time change can be implemented by emitted 3 messages:
  +
  + 1. `SetWithdrawAddress { address: recipient }` to temporarily change the
  + recipient
  + 2. `WithdrawDelegatorReward { validator }` to do a manual withdrawl from the
  + given validator
  + 3. `SetWithdrawAddress { address: env.contract.address.into() }` to change it
  + back for all future withdrawls
  +
  + [distribution docs]: https://docs.cosmos.network/v0.42/modules/distribution/
  +
  ## 0.12 -> 0.13
  - The minimum Rust supported version for 0.13 is 1.47.0. Verify your Rust
  