KVM: x86: Improve documentation for KVM_CAP_X86_BUS_LOCK_EXIT

Improve the description for the KVM_CAP_X86_BUS_LOCK_EXIT capability to
fix a few typos and grammar issues, and to clarify the purpose of the
capability.

Signed-off-by: Carlos López <clopez@suse.de>
Link: https://lore.kernel.org/r/20240424105616.29596-1-clopez@suse.de


[sean: massage changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>