Update readme Add examples section

This should address @bartvde comment at https://github.com/bartvde/ol3/commit/ce1e0fba9ae2a21ed0419da0e9f8c2f28654df90#commitcomment-2646652.

@bartvde, do you think that's good enough for now? The readme already had an "Add examples" section, so I thought this section was the proper place for this information for now.