I don't understand what point you are trying to make. As I stated, pretty much every project hoster has two repositories per project for the code and wiki. Eg for github you have github.com/[user]/[project].git and github.com/[user]/[project].wiki.git

With Google Code you can have any number of additional repositories eg the equivalent of github.com/[user]/[project].documentation.git, github.com/[user]/[project].testsuites.git, github.com/[user]/[project].androidclient.git etc

With Github you would have to create new projects which means separate issue trackers, wikis etc.