Update installation.md
Update installation.md

`s/includding/including/`
saucal/VVV,trepmal/varying-vagrant-vagrants,clreed87/VVV,clreed87/VVV,Varying-Vagrant-Vagrants/VVV,tomjn/varying-vagrant-vagrants,WybrenKoelmans/VVV,DrewAPicture/varying-vagrant-vagrants,WybrenKoelmans/VVV,Varying-Vagrant-Vagrants/VVV,saucal/VVV,DrewAPicture/varying-vagrant-vagrants,Varying-Vagrant-Vagrants/VVV,trepmal/varying-vagrant-vagrants,saucal/VVV,salcode/VVV,speartail/VVV,tomjn/varying-vagrant-vagrants,salcode/VVV,speartail/VVV