examples/skeleton: improve documentation
examples/skeleton: improve documentation

Minor refactoring and comments to make the sample app and
code examples clearer for the sample app guide.

Signed-off-by: John McNamara <af31595c36a4239b9676e9b3a777d3e2f15a6c4d@intel.com>
Acked-by: Siobhan Butler <8cf2da75f16c15b95e66f52a35c85d9ba5dc91d6@intel.com>
Acked-by: Pablo de Lara <28355d9cfe41bb8148aea0fb24f47aae8f4217a1@intel.com>

msune/dpdk,msune/dpdk,john-mcnamara-intel/dpdk,tsphillips/dpdk-fork,tsphillips/dpdk-fork,tsphillips/dpdk-fork,msune/dpdk,mixja/dpdk,john-mcnamara-intel/dpdk,venkynv/dpdk-mirror,mixja/dpdk,mixja/dpdk,msune/dpdk,mixja/dpdk,venkynv/dpdk-mirror,venkynv/dpdk-mirror,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,venkynv/dpdk-mirror,tsphillips/dpdk-fork