* Add uart_puts() and uart_gets() * Add some docs * Rework API * Formatting * Update docs/uart_driver.md Co-authored-by: Sergey Vlasov <[email protected]> * Simplify a uart_write() loop * Update platforms/avr/drivers/uart.c Co-authored-by: Joel Challis <[email protected]> Co-authored-by: Sergey Vlasov <[email protected]> Co-authored-by: Joel Challis <[email protected]>