message: Update CHANGELOG for CosmWasmClient.broadcastTx
diff: @@ -116,6 +116,9 @@ and this project adheres to
  - @cosmjs/stargate: `StargateClient.broadcastTx` now uses sync mode and then
  polls for the transaction before resolving. The timeout and poll interval can
  be configured.
  +- @cosmjs/cosmwasm-stargate: `CosmWasmClient.broadcastTx` now uses sync mode and
  + then polls for the transaction before resolving. The timeout and poll interval
  + can be configured.
  ### Deprecated
  