fix typo

Author: dadgar

website/source/docs/commands/node/drain.html.md.erb

@@ -57,7 +57,7 @@ operation is desired.
 * `-force`: Force remove allocations off the node immediately.
 * `-no-deadline`: No deadline allows the allocations to drain off the node
   without being force stopped after a certain deadline.
-* `-ignore-system`: Ignore sytem allows the drain to complete without stopping
+* `-ignore-system`: Ignore system allows the drain to complete without stopping
   system job allocations. By default system jobs are stopped last.
 * `-keep-ineligible`: Keep ineligible will maintain the node's scheduling
   ineligibility even if the drain is being disabled. This is useful when an