doc: remove some build instructions where unneeded

doc: remove some build instructions where unneeded

The build should be described only in few places,
in order to maintain up-to-date, accurate and detailed instructions.
This change is removing some of the unneeded repetitions.

Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
Acked-by: Ajit Khaparde <ajit.khaparde@broadcom.com>
Acked-by: Jay Zhou <jianjay.zhou@huawei.com>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>
Acked-by: David Marchand <david.marchand@redhat.com>