Write coordinate transformation examples

[ouzor]

Use existing guides:
https://pakillo.github.io/R-GIS-tutorial/
https://louhos.wordpress.com/2011/10/19/tilastokeskuksen-pc-axis-muotoisten-aineistojen-visualisointi-suomen-kartalla/#comments

[jlehtoma]

There's a wonderful book called Geocomputation with R that has a very useful chapter (Chapter 6 Reprojecting geographic data) on this. Perhaps we could link to this resource. Still, having contextualized (Finnish) examples would be useful too.