There are some minor syntax and command issues in debug-port document.
As commit 5febdec81a (vmm: Enable `gdbstub` on AArch64) supported
aarch64, the docs should keep consistent.
Signed-off-by: Yi Wang <foxywang@tencent.com>
This simplifies the CI process but also logical with the existing
functionality under "guest_debug" (dumping guest memory).
Fixes: #4679
Signed-off-by: Rob Bradford <robert.bradford@intel.com>