Redundancy Fix #16

Remove unnecessary things like Bit-Field Layout. Table
https://github.com/ADN-VLSI/adn_uart/blob/5802b696bce5b5410fb6dac0d85754e8d28c24de/document/adn_uart_reg.md?plain=1#L45

Multiple documents are mixed up here. If you want describe how the device is expected to operate, do it in a separate doc.