geocode: change order of lat and lon in results

[dpprdan]

Just a small change to the order of the 'lat' and 'lon' columns for geocode(). Instead of 'lon', 'lat' they are now 'lat', 'lon' so as to make it easy to copy & paste results and to resemble the order of the output arguments name, 'latlon'/'latlona'.

Thanks for considering it!

• [x] Did you run R CMD CHECK?
• [x] Did you run roxygen2::roxygenise(".")?

I ran roxygenise and it actually wrote a new man document (geom_leg.Rd), but that does not have anything to do with this PR, so I did not commit it (yet?).