message: Doc: Add introduce about binlog size in pika.conf
diff: @@ -106,6 +106,7 @@ max-conn-rbuf-size : 268435456
  # write_binlog [yes | no]
  write-binlog : yes
  # binlog file size: default is 100M, limited in [1K, 2G]
  +# slave binlog file size must be the same with master's
  binlog-file-size : 104857600
  # Automatically triggers a small compaction according statistics
  # Use the cache to store up to 'max-cache-statistic-keys' keys
  