yocto-project-qs: Created two sub-sections for the "Build" section.

yocto-project-qs: Created two sub-sections for the "Build" section.

Fixes [YOCTO #10462]

The section that shows how to build images had two examples all
within the same section.  It was suggested to place these examples
in their own sub-sections.  Good suggestion.  I broke them out into
sub-sections titled appropriately.

(From yocto-docs rev: b97918820cfa12a2d5dfbccd6c0ce22b16d65206)

Signed-off-by: Scott Rifenbark <srifenbark@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>