doc: add libcjson-dev installation in GSG
Libcjson package is needed to build command monitor of DM,
so this should be installed in the user's development machine.
@@ -126,6 +126,7 @@ To set up the ACRN build environment on the development computer:
e2fslibs-dev \
pkg-config \
libnuma-dev \
+ libcjson-dev \
liblz4-tool \
flex \
bison \
