message: docs: Add operator instructions for the testnet
diff: @@ -69,6 +69,19 @@ indexer. The only requirement is a minimum stake of 100k GRT.
  In order to register for the testnet and have testnet GRT distributed to you,
  please fill out the [testnet registration form](https://airtable.com/shrL1trS84Jf0aawP).
  +### Setting An Operator
  +
  +To set an operator for your testnet indexer, you can use the contracts CLI as follows.
  +This is similar to using Remix, except it's easier.
  +
  +```bash
  +git clone https://github.com/graphprotocol/contracts
  +cd contracts
  +
  +./cli/cli.ts -m <indexer-mnemonic> -p <ethereum-rinkeby-node> \
  + contracts staking setOperator --operator <operator-address> --allowed true
  +```
  +
  ### Network Parameters
  | Parameter | Value |
  