Add legend title in TADA_GroupedScatterPlot

[wokenny13]

Add a legend title for TADA_GroupedScatterPlot

Describe the solution you'd like:

For specifying what groups to plot on the figure, sometimes it could be unclear what groups are being plotted, such as for CountyCode. Adding a legend title would assist those who view the graph to understand what is being plotted.

[wokenny13]

Attempted to put a legend title in the plot, but it shows up to the left of the legend labels. Did try to spend some time to make it show above, but could not figure out. May be a simple item to address but is not urgent. Will comment the line of code out for now, but can be looked into if anyone wants to try to format it in the future.
legend = list( title = list(text = paste0('<b>', group_col,'<b>'), x = 0.5, y= 100), orientation = "h", xanchor = "center", x = 0.5 )

[hillarymarler]

@wokenny13 - can you link this to the branch you've been using to work on it?

[wokenny13]

#507 I believe I pushed that commit through with that small code update to this branch