update build instructions to current env
update build instructions to current env

Be a bit more explicit in the required commands and update some outdated commands. The shortlist of tweaks includes:
- Install doxygen via homebrew instead of binary package
- xmlToHtml.py had been renamed to generateDocs.py and doesn't require args
- Use local path to gulp binary
- Provide shell commands and execution directories

sosolimited/Cinder,2666hz/Cinder,morbozoo/sonyHeadphones,2666hz/Cinder,morbozoo/sonyHeadphones,sosolimited/Cinder,morbozoo/sonyHeadphones,sosolimited/Cinder,2666hz/Cinder,2666hz/Cinder,morbozoo/sonyHeadphones,sosolimited/Cinder