docs/sp_SP: Add translation of process/adding-syscalls

Translate Documentation/process/adding-syscalls.rst into Spanish.

Co-developed-by: Mauricio Fuentes <[email protected]>
Signed-off-by: Mauricio Fuentes <[email protected]>
Signed-off-by: Carlos Bilbao <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: Zildj1an