[SPARK-18461][DOCS][STRUCTUREDSTREAMING] Added more information about monitoring streaming queries

## What changes were proposed in this pull request?
<img width="941" alt="screen shot 2016-11-15 at 6 27 32 pm" src="https://cloud.githubusercontent.com/assets/663212/20332521/4190b858-ab61-11e6-93a6-4bdc05105ed9.png">
<img width="940" alt="screen shot 2016-11-15 at 6 27 45 pm" src="https://cloud.githubusercontent.com/assets/663212/20332525/44a0d01e-ab61-11e6-8668-47f925490d4f.png">

Author: Tathagata Das <tathagata.das1565@gmail.com>

Closes #15897 from tdas/SPARK-18461.