[documentation] - REGISTER_TASK.md located here can be improved

[00-linglin]

For the instructions related to: https://github.com/flare-foundation/flare-systems-deployment/blob/main/docs/REGISTER_TASK.md

additional information would be helpful, for example, please consider the following changes:

Prerequisites

1. install yarn from: https://classic.yarnpkg.com/en/docs/install

Registration tasks

If you do have a safe environment to work with you can register your entity addresses with the register-entities script and your sortition public key with the register-public-keys script.

1. clone the https://github.com/flare-foundation/flare-smart-contracts-v2 repo
2. change directory to the newly cloned repo: cd flare-smart-contracts-v2
3. fill out and store below snippet to a file named accounts.json, at the root of the flare-smart-contracts-v2 repo:

[
  {
    "identity": {
      "address": "<address>",
      "privateKey": "<private key hex>"
    },
    "submit": {
      "address": "<address>",
      "privateKey": "<private key hex>"
    },
    "submitSignatures": {
      "address": "<address>",
      "privateKey": "<private key hex>"
    },
    "signingPolicy": {
      "address": "<address>",
      "privateKey": "<private key hex>"
    },
    "delegation": {
      "address": "<address>",
      "privateKey": "<private key hex>"
    },
    "sortitionPrivateKey": "<private key hex>"
  }
]

5. create .env file using this template (eg.: for Flare network, or one of the other test networks, coston2 for example)

FLARE_RPC=rpcurl
CHAIN_CONFIG=flare|coston|coston2
ENTITIES_FILE_PATH=accounts.json

6. finally run the scripts (eg.: for Flare network, replace --network with the appropriate network as neccessary)

# initialize repository
yarn
# compile contracts
yarn c
# run entity registration
yarn hardhat --network flare deployment/tasks/register-entities
# run public key registration
yarn hardhat --network flare deployment/tasks/register-public-keys