Updating dashboard user guide doc for icehouse

Updating dashboard user guide doc for icehouse.
* New HDFS data source
* "Internal database" name change
* Relaunch functionality
* Remove reference to "job binary internal"

Partial-Implements: blueprint update-docs-icehouse

Change-Id: I87d2c48ebd37aa682582f9b1c6f8d763e207ddaf
Merge "Updating dashboard user guide doc for icehouse"