Add direnv file
Background: I just discovered this awesome utility direnv which lets you simply run some commands when you enter a directory. What makes this so awesome is that it also supports Nix and can load the shell.nix automagically.
With this change, anyone with direnv installed can once run
direnv allow . and it will:
- Load the shell.nix (provided nix is installed) which automatically fetches all dependencies
make env, except without installing anything since you don't want to install redox every time you enter the directory.