message: docs: Correct network of testnet contracts
diff: @@ -131,7 +131,7 @@ cd contracts
  ### Configuration
  -The Graph testnet contracts live on mainnet, but the subgraphs used in the
  +The Graph testnet contracts live on rinkeby, but the subgraphs used in the
  testnet (for now) are all mainnet subgraphs. This means:
  - Indexer Agent and Indexer Service must connect to rinkeby
  