Add inline // comments to all main.rs and board.rs boilerplate across 0x01-0x08 Rust drivers

- Add // comments to mod declarations, use imports, static items, and
  PICOTOOL_ENTRIES in all 8 main.rs files matching rp-hal template style
- Add //! file headers to all 8 board.rs files
- Add // comments to all board.rs use imports and HAL alias
- All 8 drivers build successfully, all 75 tests pass

drivers/0x01_uart_rust/src/board.rs

@@ -25,9 +25,14 @@
 //! OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 //! SOFTWARE.
 
+//! @file board.rs
+//! @brief Board-level HAL helpers for the UART driver
+//! @author Kevin Thomas
+//! @date 2025
+
+// Alias our HAL crate
 #[cfg(rp2350)]
 use rp235x_hal as hal;
-
 #[cfg(rp2040)]
 use rp2040_hal as hal;
 

drivers/0x01_uart_rust/src/main.rs

@@ -40,28 +40,36 @@
 #![no_std]
 #![no_main]
 
+// Board-level helpers: constants, type aliases, and init functions
 mod board;
+// UART driver module
 mod uart;
 
+// Debugging output over RTT
 use defmt_rtt as _;
+// Panic handler for RISC-V targets
 #[cfg(target_arch = "riscv32")]
 use panic_halt as _;
+// Panic handler for ARM targets
 #[cfg(target_arch = "arm")]
 use panic_probe as _;
 
+// HAL entry-point macro
 use hal::entry;
 
+// Alias our HAL crate
 #[cfg(rp2350)]
 use rp235x_hal as hal;
-
 #[cfg(rp2040)]
 use rp2040_hal as hal;
 
+// Second-stage boot loader for RP2040
 #[unsafe(link_section = ".boot2")]
 #[used]
 #[cfg(rp2040)]
 pub static BOOT2: [u8; 256] = rp2040_boot2::BOOT_LOADER_W25Q080;
 
+// Boot metadata for the RP2350 Boot ROM
 #[unsafe(link_section = ".start_block")]
 #[used]
 #[cfg(rp2350)]
@@ -97,6 +105,7 @@ fn main() -> ! {
     }
 }
 
+// Picotool binary info metadata
 #[unsafe(link_section = ".bi_entries")]
 #[used]
 pub static PICOTOOL_ENTRIES: [hal::binary_info::EntryAddr; 5] = [