* Add uart_puts() and uart_gets() * Add some docs * Rework API * Formatting * Update docs/uart_driver.md Co-authored-by: Sergey Vlasov <sigprof@gmail.com> * Simplify a uart_write() loop * Update platforms/avr/drivers/uart.c Co-authored-by: Joel Challis <git@zvecr.com> Co-authored-by: Sergey Vlasov <sigprof@gmail.com> Co-authored-by: Joel Challis <git@zvecr.com>