message: chore: print warning about default miner key
  Print the warning when running `ckb init`. Remind user to change the default
  block assembler config before mining.
diff: @@ -46,5 +46,11 @@ pub fn init(args: InitArgs) -> Result<(), ExitCode> {
  args.locator.export_specs()?;
  }
  + eprintln!(
  + "**Notice**: \
  + If you want to mine CKB, please make sure to create your own \
  + private key and change the block_assembler config in ckb.toml."
  + );
  +
  Ok(())
  }
  