Add a short section on attribute table

[brunj7]

Although in this first workshop we are not focusing too much on the data aspects of those layers, we should introduce how to access the attribute table of the feature layers

[brunj7]

I added a sub-section on this topic at the end of Step 1 (see 4d3485f). Still not 100% convinced it is the best spot. Step 2 when we start using the first attribute could also be an option