doc: Edits to the Overview and kernel primer

Fixed typo in system_fundamentals.  Acronyms FIFO and LIFO
defined with capital letters in kernel_fundamentals. Added bold
to paragraph lists to enhance readability in application_fundamentals

Added lots of :dfn: syntax for better interlinking to API.

Corrected whitespace for sub-bullet directive.

Change-Id: If6c5bc78746686d1a4986974f1b56bf9b2caebca
Signed-off-by: L.S. Cook <leonax.cook@intel.com>