docs: Fix markdown style (header levels, block syntax highlight)

README.md

@@ -8,43 +8,48 @@ Firmware source for the Raspberry Pi Debug Probe SWD/UART accessory. Can also be
 
 [Raspberry Pi Pico 2 product page](https://www.raspberrypi.com/products/raspberry-pi-pico-2/)
 
-# Documentation
+## Documentation
 
 Debug Probe documentation can be found at the [Raspberry Pi Microcontroller Documentation portal](https://www.raspberrypi.com/documentation/microcontrollers/debug-probe.html#about-the-debug-probe).
 
-# Hacking
+## Hacking
 
 For the purpose of making changes or studying of the code, you may want to compile the code yourself.
 
 First, clone the repository:
-```
+```bash
 git clone https://github.com/raspberrypi/debugprobe
 cd debugprobe
 ```
+
 Initialize and update the submodules:
-```
+```bash
  git submodule update --init --recursive
 ```
+
 Then create and switch to the build directory:
-```
+```bash
  mkdir build
  cd build
 ```
+
 If your environment doesn't contain `PICO_SDK_PATH`, then either add it to your environment variables with `export PICO_SDK_PATH=/path/to/sdk` or add `-DPICO_SDK_PATH=/path/to/sdk` to the arguments to CMake below.
 
 Run cmake and build the code:
-```
+```bash
  cmake ..
  make
 ```
+
 Done! You should now have a `debugprobe.uf2` that you can upload to your Debug Probe via the UF2 bootloader.
 
 ## Building for the Pico 1
 
 If you want to create the version that runs on the Pico, then you need to invoke `cmake` in the sequence above with the `DEBUG_ON_PICO=ON` option:
-```
+```bash
 cmake -DDEBUG_ON_PICO=ON ..
 ```
+
 This will build with the configuration for the Pico and call the output program `debugprobe_on_pico.uf2`, as opposed to `debugprobe.uf2` for the accessory hardware.
 
 Note that if you first ran through the whole sequence to compile for the Debug Probe, then you don't need to start back at the top. You can just go back to the `cmake` step and start from there.
@@ -56,16 +61,17 @@ If using an existing debugprobe clone:
 - You must also sync and update submodules.
 - `PICO_SDK_PATH` must point to a version 2.0.0 or greater install.
 
-```
+```bash
 git submodule sync
 git submodule update --init --recursive
 mkdir build-pico2
 cd build-pico2
 cmake -DDEBUG_ON_PICO=1 -DPICO_BOARD=pico2 ../
 ```
+
 This will build with the configuration for the Pico 2 and call the output program `debugprobe_on_pico2.uf2`.
 
-# AutoBaud
+## AutoBaud Mode
 
 Mode which automatically detects and sets the UART baud rate as data arrives.