Update URLs that were pointing to the old sourceforge website.
For the "Building" documentation, the old wiki page (currently down)
has almost the same content of the current Building documentation,
except the latter is more up-to-date and is available.
Update URLs that were pointing to the old sourceforge website. For the "Building" documentation, the old wiki page (currently down) has almost the same content of the current Building documentation, except the latter is more up-to-date and is available.