`.gitignore`: Ignore the nvm git clone in the 'nvm' directory in config
`.gitignore`: Ignore the nvm git clone in the 'nvm' directory in config

Following #863 the folder `config/nvm/` was showing as "Untracked files" by Git
miya0001/VVV,clreed87/VVV,miya0001/VVV,tpkemme/TVV,Varying-Vagrant-Vagrants/VVV,TobiasBg/Varying-Vagrant-Vagrants,salcode/VVV,tpkemme/TVV,TobiasBg/Varying-Vagrant-Vagrants,tomjn/varying-vagrant-vagrants,cfoellmann/VVV,Varying-Vagrant-Vagrants/VVV,trepmal/varying-vagrant-vagrants,trepmal/varying-vagrant-vagrants,tpkemme/TVV,cfoellmann/VVV,tpkemme/TVV,saucal/VVV,erikjoling/VVV,DrewAPicture/varying-vagrant-vagrants,salcode/VVV,WybrenKoelmans/VVV,tomjn/varying-vagrant-vagrants,saucal/VVV,clreed87/VVV,speartail/VVV,WybrenKoelmans/VVV,erikjoling/VVV,Varying-Vagrant-Vagrants/VVV,DrewAPicture/varying-vagrant-vagrants,saucal/VVV,speartail/VVV