message: Link cosmwasm-storage in overview
diff: @@ -30,6 +30,9 @@ This code is compiled into Wasm bytecode as part of the smart contract.
  - [cosmwasm-std](https://github.com/CosmWasm/cosmwasm/tree/master/packages/std) -
  A crate in this workspace. Provides the bindings and all imports needed to
  build a smart contract.
  +- [cosmwasm-storage](https://github.com/CosmWasm/cosmwasm/tree/master/packages/storage) -
  + A crate in this workspace. This optional addition to `cosmwasm-std` includes
  + convenience helpers for interacting with storage.
  **Building contracts:**
  