Documentation: KVM: make corrections to halt-polling.rst

Module parameters are in sysfs, not debugfs, so change that.

Remove superfluous "that" following "Note:".
Hyphenate "system-wide" values.
Hyphenate "trade-off".

Don't treat "denial of service" as a verb.

Signed-off-by: Randy Dunlap <[e-mail]>
Cc: Suraj Jitindar Singh <[e-mail]>
Cc: Paolo Bonzini <[e-mail]>
Cc: Sean Christopherson <[e-mail]>
Cc: [e-mail]
Cc: Jonathan Corbet <[e-mail]>
Cc: [e-mail]
Signed-off-by: Jonathan Corbet <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

Documentation/virt/kvm/halt-polling.rst

···
 |			| function.		    |			      |
 +-----------------------+---------------------------+-------------------------+
 
-These module parameters can be set from the debugfs files in:
+These module parameters can be set from the sysfs files in:
 
 	/sys/module/kvm/parameters/
 
-Note: that these module parameters are system wide values and are not able to
+Note: these module parameters are system-wide values and are not able to
       be tuned on a per vm basis.
 
 Any changes to these parameters will be picked up by new and existing vCPUs the
···
   global max polling interval (halt_poll_ns) then the host will always poll for the
   entire block time and thus cpu utilisation will go to 100%.
 
-- Halt polling essentially presents a trade off between power usage and latency and
+- Halt polling essentially presents a trade-off between power usage and latency and
   the module parameters should be used to tune the affinity for this. Idle cpu time is
   essentially converted to host kernel time with the aim of decreasing latency when
   entering the guest.
 
 - Halt polling will only be conducted by the host when no other tasks are runnable on
   that cpu, otherwise the polling will cease immediately and schedule will be invoked to
-  allow that other task to run. Thus this doesn't allow a guest to denial of service the
-  cpu.
+  allow that other task to run. Thus this doesn't allow a guest to cause denial of service
+  of the cpu.