docs: kvm: fix WARNINGs from api.rst

Use the api number 134 for KVM_GET_XSAVE2, instead of 42, which has been
used by KVM_GET_XSAVE.
Also, fix the WARNINGs of the underlines being too short.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Wei Wang <wei.w.wang@intel.com>
Tested-by: Stephen Rothwell <sfr@canb.auug.org.au>
Message-Id: <20220120045003.315177-1-wei.w.wang@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Author: wei-w-wang

Documentation/virt/kvm/api.rst

@@ -5545,8 +5545,8 @@ the trailing ``'\0'``, is indicated by ``name_size`` in the header.
 The Stats Data block contains an array of 64-bit values in the same order
 as the descriptors in Descriptors block.
 
-4.42 KVM_GET_XSAVE2
-------------------
+4.134 KVM_GET_XSAVE2
+--------------------
 
 :Capability: KVM_CAP_XSAVE2
 :Architectures: x86
@@ -7363,7 +7363,7 @@ trap and emulate MSRs that are outside of the scope of KVM as well as
 limit the attack surface on KVM's MSR emulation code.
 
 8.28 KVM_CAP_ENFORCE_PV_FEATURE_CPUID
------------------------------
+-------------------------------------
 
 Architectures: x86