Documentation: KVM: update msr.rst reference

Changeset daec8d40 ("Documentation: KVM: add separate directories for architecture-specific documentation")
renamed: Documentation/virt/kvm/msr.rst
to: Documentation/virt/kvm/x86/msr.rst.

Update its cross-reference accordingly.

Fixes: daec8d40 ("Documentation: KVM: add separate directories for architecture-specific documentation")
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Link: https://lore.kernel.org/r/5652b7f5caff3b817a660b75f1f319a2f8962380.1656234456.git.mchehab@kernel.orgSigned-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/virt/kvm/api.rst

@@ -7670,7 +7670,7 @@ architecture-specific interfaces.  This capability and the architecture-
 specific interfaces must be consistent, i.e. if one says the feature
 is supported, than the other should as well and vice versa.  For arm64
 see Documentation/virt/kvm/devices/vcpu.rst "KVM_ARM_VCPU_PVTIME_CTRL".
-For x86 see Documentation/virt/kvm/msr.rst "MSR_KVM_STEAL_TIME".
+For x86 see Documentation/virt/kvm/x86/msr.rst "MSR_KVM_STEAL_TIME".
 
 8.25 KVM_CAP_S390_DIAG318
 -------------------------