message: Log the era_id of linear chain.
diff: @@ -108,8 +108,9 @@ where
  },
  Event::PutBlockResult(block_header) => {
  let block_hash = block_header.hash();
  + let era_id = block_header.era_id();
  // Using `Display` impl for the `block_hash` to not truncate it.
  - info!(?block_hash, "Linear chain block stored.");
  + info!(?block_hash, ?era_id, "Linear chain block stored.");
  effect_builder.handle_linear_chain_block(block_header)
  .event(move |signature| Event::NewFinalitySignature(block_hash, signature))
  },
  