doc: add ZUC shared library limitation
doc: add ZUC shared library limitation

ZUC PMD cannot be built as a shared library, due to
the fact that some assembly code in the underlying libsso
library is not relocatable.
This will be fixed in the future, but for the moment,
it is added as a limitationof the PMD.

Signed-off-by: Pablo de Lara <28355d9cfe41bb8148aea0fb24f47aae8f4217a1@intel.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk