message: Document new --code argument in CLI
diff: ## HEAD
  - @cosmjs/cli: Now supports HTTPs URLs for `--init` code sources.
  +- @cosmjs/cli: Now supports adding code directly via `--code`.
  - @cosmjs/cosmwasm: Rename `CosmWasmClient.getNonce` method to `.getSequence`.
  - @cosmjs/cosmwasm: Remove `RestClient` class in favour of new modular
  `LcdClient` class from @cosmjs/sdk38.
  