initializing sub modules requires auth

[devilsclaw]

Describe the bug
I was fallowing the gut of how to use nix to compile the project and the part where . it tells you to use the command

git submodule update --init --recursive

requires a user name and password for wire-server-enterprise

To Reproduce
Steps to reproduce the behavior:

1. git clone https://github.com/wireapp/wire-server.git
2. git submodule update --init --recursive

Expected behavior
It should allow pulling the source since its needed for building from source

[chrishowell211313]

Navigating to https://github.com/wireapp/wire-server-enterprise returns a 404 error, so I assume the repository URL is either incorrect or the repository is private.