docs: Document the hash storage smart contract address (#195)

* Update 4-storage.md

* docs: fix typo on portal intro

packages/docs/docs/guides/3-Portal-API/0-portal-intro.md

@@ -94,6 +94,6 @@ const result = await axios.get('https://api.request.network/requests/' + request
 });
 ```
 
-The expected result should but a list of requests with amounts and currencies. Depending on your currency, some amounts seem too big. We will see later how to display amounts properly.
+The expected result should be a list of requests with amounts and currencies. Depending on your currency, some amounts seem too big. We will see later how to display amounts properly.
 
 As you can see, manipulating requests with the Portal API is very straight-forward. What you can notice is the use of `request.requestInput.expectedAmount` and `request.requestInput.currency`. We will detail on the next page how to manipulate different details of the request. You can also have more details on the [Portal API Docs](/portal).

packages/docs/docs/guides/7-protocol/4-storage.md

@@ -30,3 +30,13 @@ We use Ethereum to store IPFS hashes. The hashes are stored as event logs of a s
 The Ethereum smart contracts are also used to enforce the fee cost of storing a block to Request. The user will store the size of the file being stored in addition to the hash. A fee, related to this hash, will be paid in Ether when storing the hash.
 
 For our solution, we use additional smart contracts for fee verification. Using external smart contracts allows us to implement different fee rules in the future. More information can be found in the ethereum-storage repository.
+
+The RequestHashStorage smart contract address can be found on [GitHub](https://github.com/RequestNetwork/requestNetwork/blob/1f24dd17353497cc6ee21abf2d7bfda9e63d2ba5/packages/smart-contracts/artifacts/RequestHashStorage/artifacts.json)
+```json
+ "mainnet": {
+  "address": "0x24a66afda3666fb0202f439708ece45c8121a9bb"
+},
+"rinkeby": {
+  "address": "0x309a3a9898f9cafc26499243a980992156671e5e"
+}
+```