message: Update README.md
  some typos
diff: @@ -273,10 +273,10 @@ pub struct Region {
  If you followed the [instructions above](#Creating), you should have a runable
  smart contract. You may notice that all of the Wasm exports are taken care of by
  -`lib.rs`, which should shouldn't need to modify. What you need to do is simply
  -look in `contract.rs` and implement `instantiate` and `execute` functions,
  -defining your custom `InstantiateMsg` and `ExecuteMsg` structs for parsing your
  -custom message types (as json):
  +`lib.rs`, which you shouldn't need to modify. What you need to do is simply look
  +in `contract.rs` and implement `instantiate` and `execute` functions, defining
  +your custom `InstantiateMsg` and `ExecuteMsg` structs for parsing your custom
  +message types (as json):
  ```rust
  #[entry_point]
  @@ -305,8 +305,8 @@ pub fn migrate(deps: DepsMut, env: Env, msg: MigrateMsg) -> Result<Response, Con
  The low-level `db_read` and `db_write` imports are nicely wrapped for you by a
  `Storage` implementation (which can be swapped out between real Wasm code and
  test code). This gives you a simple way to read and write data to a custom
  -sub-database that this contract can safely write as it wants. It's up to you to
  -determine which data you want to store here:
  +sub-database that this contract can safely write to as it wants. It's up to you
  +to determine which data you want to store here:
  ```rust
  /// Storage provides read and write access to a persistent storage.
  