message: update readme for sdk safe read methods
diff: @@ -299,10 +299,10 @@ This call is used to view a specific safe in the layer 2 network in which the Ca
  This method is invoked with the following parameters:
  - safe address
  -This method returns a promise for an object that is a `Safe` type:
  +This method returns a promise for an object that contains a `Safe` and the block number at which the subgraph was last indexed:
  Which can be called like this:
  ```js
  -let safeDetails = await safes.viewSafe(safeAddress);
  +let safeDetails = await safes.viewSafe(safeAddress); // returns { safe: Safe | undefined; blockNumber: number; }
  ```
  ### `Safes.view`
  @@ -311,7 +311,7 @@ This call is used to view all the gnosis safes owned by a particular address in
  This method is invoked with the following parameters:
  - Optionally the address of a safe owner. If no address is supplied, then the default account in your web3 provider's wallet will be used.
  -This method returns a promise that includes an array of all the gnosis safes owned by the specified address. The result is an object that is a `Safe[]` type which conforms to the `Safe` shape below:
  +This method returns a promise that includes an array of all the gnosis safes owned by the specified address. The result is an object contains a `Safe[]` type which conforms to the `Safe` shape below, and the block number at which the subgraph was last indexed:
  ```ts
  export type Safe = DepotSafe | PrepaidCardSafe | MerchantSafe | ExternalSafe;
  @@ -342,7 +342,7 @@ interface PrepaidCardSafe extends BaseSafe {
  Which can be called like this:
  ```js
  -let safeDetails = await safes.view();
  +let safeDetails = await safes.view(); // returns { safes: Safe[]; blockNumber: number; }
  ```
  ### `Safes.sendTokensGasEstimate`
  