docs: kvm: fix build warnings

Fix some small build warnings. The title underline was too short in some
cases and a code block was not indented.

Documentation/virt/kvm/api.rst:7216: WARNING: Title underline too short.

Fixes: 6dba9403 ("KVM: x86: Introduce KVM_GET_SREGS2 / KVM_SET_SREGS2")
Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Link: https://lore.kernel.org/r/20210722100356.635078-3-ciorneiioana@gmail.comSigned-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/virt/kvm/api.rst

@@ -5077,7 +5077,7 @@ of bytes successfully copied is returned. If the call completes successfully
 then ``length`` is returned.
 
 4.131 KVM_GET_SREGS2
-------------------
+--------------------
 
 :Capability: KVM_CAP_SREGS2
 :Architectures: x86
@@ -5090,7 +5090,7 @@ This ioctl (when supported) replaces the KVM_GET_SREGS.
 
 ::
 
-struct kvm_sregs2 {
+        struct kvm_sregs2 {
                 /* out (KVM_GET_SREGS2) / in (KVM_SET_SREGS2) */
                 struct kvm_segment cs, ds, es, fs, gs, ss;
                 struct kvm_segment tr, ldt;
@@ -5100,7 +5100,7 @@ struct kvm_sregs2 {
                 __u64 apic_base;
                 __u64 flags;
                 __u64 pdptrs[4];
-};
+        };
 
 flags values for ``kvm_sregs2``:
 
@@ -5110,7 +5110,7 @@ flags values for ``kvm_sregs2``:
 
 
 4.132 KVM_SET_SREGS2
-------------------
+--------------------
 
 :Capability: KVM_CAP_SREGS2
 :Architectures: x86
@@ -7213,7 +7213,7 @@ supported in the host. A VMM can check whether the service is
 available to the guest on migration.
 
 8.33 KVM_CAP_HYPERV_ENFORCE_CPUID
------------------------------
+---------------------------------
 
 Architectures: x86