Documentation problems

[benlaurie]

Firstly, section 1.3 (https://lowrisc.org/sonata-system/doc/guide/building-examples.html) actually has section 2.2 (https://lowrisc.org/sonata-system/doc/dev/toolchain-setup.html) as a prerequisite - this is highly confusing, 2.2 should come first.

Secondly xmake config --board=sonata is incorrect, it also needs the location of the sdk specified: xmake config --sdk=$LLVM_PATH/builds/cheriot-llvm --board=sonata ought to work if 2.2 has just been done. :-)

Thirdly, the uf2 converter is a prerequisite that is not documented: https://github.com/makerdiary/uf2utils?tab=readme-ov-file