This indents existing code examples that are not indented yet,
just to make future conversion to Sphinx markup easier to review.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Message-Id: <20200910221526.10041-7-ehabkost@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>