docs: fix rendering for code blocks in SPM

Two sample build command code blocks are not correctly
rendered by the documentation generator.

Fix that by adding newlines.

Signed-off-by: Nicola Mazzucato <nicola.mazzucato@arm.com>
Change-Id: I1bb075ea4fc8e3230307548e40daecf2a79bae8d
1 file changed