docs: old screenshot from Event Reports app causes confusion

[gassims]

The screenshot of the Event Reports app here seems to cause confusion since the UI is different/older and in the previous app it portrays the text 'Aggregated values' vs 'Events' giving the impression that it's possible to get to the 'aggregated' dataset values from the app. This impression came from this post: https://community.dhis2.org/t/event-visualiser-reports/50104

Recommendation: adding a screenshot from the latest version?

[adityaacse]

Hi @gassims, I am interested in working on this task, please assign it to me.