docs: i386: pc: Avoid mentioning limit of maximum vCPUs

docs: i386: pc: Avoid mentioning limit of maximum vCPUs

Different versions of PC machine support different maximum vCPUs, and
even different features have limits on the maximum number of vCPUs (
For example, if x2apic is not enabled in the TCG case, the maximum of
255 vCPUs are supported).

It is difficult to list the maximum vCPUs under all restrictions. Thus,
to avoid confusion, avoid mentioning specific maximum vCPU number
limitations here.

Suggested-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-ID: <20240606085436.2028900-1-zhao1.liu@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>