message: include avalanche testnet settings in .env.sample
diff: @@ -29,6 +29,13 @@ LEDGER_EMISSION_TOKEN_CONTRACT_ADDRESS="0x610178dA211FEF7D417bC0e6FeD39F05609AD7
  # site like etherscan or bscscan eg: https://testnet.bscscan.com/address/0x610178dA211FEF7D417bC0e6FeD39F05609AD788
  LEDGER_FIRST_BLOCK="0"
  +# use for Avalanche testnet
  +#LEDGER_ETH_JSON_RPC_URL="https://api.avax-test.network/ext/bc/C/rpc"
  +#LEDGER_ETH_WS_URL="wss://api.avax-test.network/ext/bc/C/ws"
  +#LEDGER_ETH_NETWORK="avalanchetestnet"
  +#LEDGER_EMISSION_TOKEN_CONTRACT_ADDRESS="0x91883251A8964dDB40F07Bc55298284a07431d1d"
  +#LEDGER_FIRST_BLOCK="11573290" # if using the public websockets, pick a recent block from testnet.snowtrace.io
  +
  # Where to find uploaded documents, relative to the api-server directory:
  DOC_UPLOAD_PATH="./upload/"
  