doc: Improve the contribution documentation

.github/workflows/verify-and-test.yml

@@ -40,7 +40,7 @@ jobs:
 
       - name: Validate JSON
         run: |
-          jsonschema -i ./json/linea-goerli-token-shortlist.json ./json/schema/l2-token-list-schema.json
+          jsonschema -i ./json/linea-sepolia-token-shortlist.json ./json/schema/l2-token-list-schema.json
 
   verify_mainnet_shortlist:
     runs-on: ubuntu-latest

README.md

@@ -14,7 +14,8 @@ If you want to add a token or validate an addition, please follow the procedures
 If you represent a project with a token on Linea, it's beneficial to add it to the shortlist. Tokens on this list are reflected in the UI of the Linea canonical bridge.
 
 > [!IMPORTANT]
-> Before adding a new token, you must verify the token's smart contract. This ensures the authenticity and security of the token. Contract verification should be done through [LineaScan's](https://lineascan.build/) or [Etherscan's](https://etherscan.io/) contract verification tools.
+> Before adding a new token, you must verify the token's smart contract on an explorer. This ensures the authenticity and security of the token. Contract verification should be done through [LineaScan's](https://lineascan.build/verifyContract) or via Hardhat's plugin ([`hardhat-verify`](https://hardhat.org/hardhat-runner/plugins/nomicfoundation-hardhat-verify)).
+> The same verification should be done on Ethereum L1 and Linea if necessary.
 
 To add a new token:
 
@@ -28,7 +29,7 @@ cd linea-token-list
 git checkout -b feat/<token-name>
 ```
 
-2. Fill out the [./json/linea-goerli-token-shortlist.json](./json/linea-mainnet-token-shortlist.json) with your token's information. Make sure you adhere to the [guidelines](#guidelines).
+2. Fill out the [linea-mainnet-token-shortlist.json](./json/linea-mainnet-token-shortlist.json) with your token's information. Make sure you adhere to the [guidelines](#guidelines).
 
 Example: