[shinyReport("transmitters")] Add summary table in Detections per hour tab

[fmaron]

Is your feature request related to a problem? Please describe.
Add a summary table for detections per hour.

Describe the solution you'd like
Add a summary table with the data used for plotting.

Describe alternatives you've considered
We should think about how to arrange this summary table since there are 2 subtabs on this page. It might be better to add the summary table below the plot instead of adding it in the left panel.

Additional context
Luciana's comment:

"I'm thinking if it might be useful to be able to export summary data for detections per hour"

[fjaine]

The challenge lies in the fact that the two tabs depend on the same data / summary output. One solution mentioned by @fmaron would be to have a more comprehensive summary table beneath the plots that can be downloaded by users