[SPARK-4889] update history server example cmds

Author: Ryan Williams <ryan.blake.williams@gmail.com>

Closes #3736 from ryan-williams/hist and squashes the following commits:

421d8ff [Ryan Williams] add another random typo fix
76d6a4c [Ryan Williams] remove hdfs example
a2d0f82 [Ryan Williams] code review feedback
9ca7629 [Ryan Williams] [SPARK-4889] update history server example cmds

(cherry picked from commit cdb2c645ab769a8678dd81cff44a809fcfa4420b)
Signed-off-by: Andrew Or <andrew@databricks.com>