docs/commandline: Fix formatting issues

docs/commandline: Fix formatting issues

For 'dom0_max_vcpus' and 'hvm_debug', markdown was interpreting the text as
regular text, and reflowing it as a regular paragraph, leading to a single
line as output.  Reformat them as code blocks inside blockquote blocks, which
causes them to take their precise whitespace layout.

For 'psr', the bullet point was incorrectly delineated from paragraph text,
causing it to be reflowed.  Alter the formatting to include the CMT-specific
options as sub-bullets of the overall CMT resource.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Ian Campbell <Ian.Campbell@citrix.com>
Release-acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
CC: Ian Jackson <Ian.Jackson@eu.citrix.com>
CC: Wei Liu <wei.liu2@citrix.com>