readme: Document some build requirements
readme: Document some build requirements

Signed-off-by: Chad Versace <a557f7f75bf28dc19ac99107f5cc7cd6b3fbdb1a@linux.intel.com>

dcbaker/waffle,maurossi/waffle,yinquan529/waffle-gl-waffle,evelikov/waffle,fjhenigman/waffle,fjhenigman/waffle,yinquan529/waffle-gl-waffle,waffle-gl/waffle,chadversary/waffle,evelikov/waffle,waffle-gl/waffle,evelikov/waffle,janesma/waffle,waffle-gl/waffle,maurossi/waffle,dcbaker/waffle,yinquan529/waffle-gl-waffle,waffle-gl/waffle,maurossi/waffle,chadversary/waffle,janesma/waffle,chadversary/waffle,dcbaker/waffle,fjhenigman/waffle,janesma/waffle