I'm trying to build the .NET Core SDK on FreeBSD but I'm having trouble with the documentation.
The documentation says I just have to initialize the submodules in the source-build repo and run ./build.sh. But this produces only the following output:

Unsupported OS 'FreeBSD' detected. Downloading linux-x64 tools.
Installing dotnet cli...
Installing dotnet 3.0 preview1 cli...
Restoring BuildTools version 3.0.0-preview4-04104-01...

Later in the documentation it says that

git submodule update --init --recursive [...] will initialize the submodules and clone the repos under the src folder if they haven't been initialized.

But after running this command, my src folder contains only the subfolders netcorecli-fsc and reference-assemblies, which are not all required repos I think. As the documentation says, I expected at least core-setup, standard, corefx and coreclr to be cloned into the src folder.
This would also explain why there is no bin folder in my source-build repo after running ./build.sh as described in the documentation.
If the scripts don't work under FreeBSD, I expect at least an error, otherwise I assume that everything has been built, which is not the case here.

So, am I doing something wrong or is the documentation incorrect or out of date?