Review and Improve slides after esLibre presentation

[acs]

Yesterday I did the workshop for the first time with the 1.1 version.

https://speakerdeck.com/acs/a-practical-introduction-to-big-data

• 1 hour is not enough
• Power samples showing the DKIW evolution are needed
• The demo is better done directly without slides, in special showing the Spark web ui.

[acs]

Uploaded v1.2 now edited from LibreOffice completely.