doc: add generic build instructions for sample apps

Moved duplicated, and occasionally outdated, doc sections from each
of the sample app guides chapters to a common chapter at the start.

This reduces the duplication in the docs and provides a single
point of reference for compiling the sample apps.

Signed-off-by: Herakliusz Lipiec <herakliusz.lipiec@intel.com>
Signed-off-by: Marko Kovacevic <marko.kovacevic@intel.com>