message: Update: docs after `metamask` to async refactor
diff: @@ -277,28 +277,28 @@ import { metamask } from 'colony-wallet/providers'; // metamask();
  ### `metamask`
  ```js
  -metamask([ProviderArguments: Object])
  +await metamask([ProviderArguments: Object])
  ```
  -This method returns an provider instance object, instantiated with the necessary prop fields.
  +This method returns a `Promise`, which after resolving, will return an provider instance object, instantiated with the necessary prop fields.
  -This provider use the in-page `Web3` provider injected by the [Metamask extension](https://github.com/MetaMask/metamask-extension), if available.
  +This provider uses the in-page `Web3` provider injected by the [Metamask extension](https://github.com/MetaMask/metamask-extension), if available.
  See [`ProviderArgumentsType`](../src/flowtypes.js#L94-L98) in [`flowtypes.js`](../src/flowtypes.js) for how the arguments object looks like.
  -The only _(optional)_ prop that this method will take is `network`. _(defaults to "homestead")_
  +The only _(optional)_ prop that this method will take is `network` _(defaults to "homestead")_ as part of the `ProvidersArgument` Object.
  ```js
  import { metamask } from 'colony-wallet/providers';
  -const provider = metamask({
  +const provider = await metamask({
  network: 'homestead'
  });
  // { chainId: '', ensAddress: '', ... }
  // Or just use the defaults if you just want to go on mainnet.
  -const providerDefaults = metamask();
  +const providerDefaults = await metamask();
  ```
  ### `etherscan`
  @@ -313,7 +313,7 @@ Even though it will work out of the box, it is highly recommended that you pass
  See [`ProviderArgumentsType`](../src/flowtypes.js#L94-L98) in [`flowtypes.js`](../src/flowtypes.js) for how the arguments object looks like.
  -The only two _(optional)_ props that this method will take are `network` and `apiKey`.
  +The only two _(optional)_ props that this method will take are `network` and `apiKey` as part of the `ProvidersArgument` Object.
  ```js
  import { etherscan } from 'colony-wallet/providers';
  @@ -338,7 +338,7 @@ Even though it will work out of the box, it is highly recommended that you pass
  See [`ProviderArgumentsType`](../src/flowtypes.js#L94-L98) in [`flowtypes.js`](../src/flowtypes.js) for how the arguments object looks like.
  -The only two _(optional)_ props that this method will take are `network` and `apiKey`.
  +The only two _(optional)_ props that this method will take are `network` and `apiKey` as part of the `ProvidersArgument` Object.
  ```js
  import { infura } from 'colony-wallet/providers';
  