doc: Set correct syntax highlighting style

Several code blocks do not specify a language for syntax
highlighting. This results in Sphinx using a default highlighter
which is Python.

This patch adds the correct language to each code block that doesn't
already specify it.

Change-Id: Icce1949aabfdc11a334a42d49edf55fa673cddc3
Signed-off-by: Paul Beesley <paul.beesley@arm.com>
diff --git a/docs/components/secure-partition-manager-design.rst b/docs/components/secure-partition-manager-design.rst
index 31276cd..88052c5 100644
--- a/docs/components/secure-partition-manager-design.rst
+++ b/docs/components/secure-partition-manager-design.rst
@@ -130,7 +130,7 @@
 Then build TF-A with SPM support and include the Standalone MM Secure Partition
 image in the FIP:
 
-::
+.. code:: shell
 
     BL32=path/to/standalone/mm/sp BL33=path/to/bl33.bin \
     make PLAT=fvp ENABLE_SPM=1 ARM_BL31_IN_DRAM=1 fip all