Add note about lowercasing usernames to userpass docs
Add note about lowercasing usernames to userpass docs

joelthompson/vault,mgk/vault,hashicorp/vault,tallpauley/vault,kingland/vault,hashicorp/vault,kingland/vault,lemondrank/vault,lirao/vault,hashicorp/vault,naunga/vault,hartsock/vault,wjam/vault,hartsock/vault,joelthompson/vault,wjam/vault,Caiyeon/vault,Aloomaio/vault,lemondrank/vault,joelthompson/vault,hartsock/vault,naunga/vault,kingland/vault,hashicorp/vault,mgk/vault,rnaveiras/vault,Caiyeon/vault,hashicorp/vault,deverton/hashicorp-vault,Aloomaio/vault,hashicorp/vault,rnaveiras/vault,lirao/vault,MonsantoCo/vault,Aloomaio/vault,deverton/hashicorp-vault,joelthompson/vault,tallpauley/vault,kingland/vault,MonsantoCo/vault,kingland/vault,quixoten/vault,mgk/vault,rnaveiras/vault,hartsock/vault,mgk/vault,rnaveiras/vault,hartsock/vault,quixoten/vault,rnaveiras/vault,Aloomaio/vault,quixoten/vault,quixoten/vault