message: refreshed some of the technical details in the readme file
diff: @@ -106,6 +106,7 @@ extern "C" fn deallocate(pointer: u32);
  extern "C" fn init(env_ptr: u32, msg_ptr: u32) -> u32;
  extern "C" fn handle(env_ptr: u32, msg_ptr: u32) -> u32;
  extern "C" fn query(msg_ptr: u32) -> u32;
  +extern "C" fn migrate(env_ptr: u32, msg_ptr: u32) -> u32;
  ```
  `allocate`/`deallocate` allow the host to manage data within the Wasm VM. If
  @@ -122,15 +123,25 @@ The imports provided to give the contract access to the environment are:
  // A complete documentation those functions is available in the VM that provides them:
  // https://github.com/CosmWasm/cosmwasm/blob/0.7/lib/vm/src/instance.rs#L43
  //
  -// TODO: use feature switches to enable precompile dependencies in the future,
  -// so contracts that need less
  extern "C" {
  fn db_read(key: *const c_void) -> u32;
  - fn db_write(key: *const c_void, value: *mut c_void) -> i32;
  - fn db_remove(key: *const c_void) -> i32;
  + fn db_write(key: *const c_void, value: *mut c_void);
  + fn db_remove(key: *const c_void);
  +
  + // scan creates an iterator, which can be read by consecutive next() calls
  + #[cfg(feature = "iterator")]
  + fn db_scan(start: *const c_void, end: *const c_void, order: i32) -> i32;
  + #[cfg(feature = "iterator")]
  + fn db_next(iterator_id: u32) -> u32;
  +
  fn canonicalize_address(human: *const c_void, canonical: *mut c_void) -> i32;
  fn humanize_address(canonical: *const c_void, human: *mut c_void) -> i32;
  +
  + // query_chain will launch a query on the chain (import)
  + // different than query which will query the state of the contract (export)
  + fn query_chain(request: *const c_void) -> u32;
  }
  +
  ```
  (from
  