add staking-abi link pr#289

Author: 0xa3k5

website/src/pages/en/indexing/overview.mdx

@@ -772,7 +772,7 @@ Once an Indexer has staked GRT in the protocol, the [Indexer components](/indexi
 
 1. Open the [Remix app](https://remix.ethereum.org/) in a browser
 
-2. In the `File Explorer` create a file named **Staking.abi** with the staking ABI.
+2. In the `File Explorer` create a file named **Staking.abi** with the [staking ABI](https://raw.githubusercontent.com/graphprotocol/contracts/mainnet-deploy-build/build/abis/Staking.json).
 
 3. With `Staking.abi` selected and open in the editor, switch to the `Deploy and run transactions` section in the Remix interface.