Update aws-ec2.html.md
Update aws-ec2.html.md

clarify, and make more explicit, the language around the default AWS public certificate
peteryhwong/vault,hartsock/vault,tallpauley/vault,jmhardison/vault,jam-pot/vault,jgcallero/vault,cimarron-pistoncloud/vault,rnaveiras/vault,cimarron-pistoncloud/vault,hartsock/vault,mgk/vault,danielsomerfield/vault,Caiyeon/vault,lemondrank/vault,deverton/hashicorp-vault,lemondrank/vault,tallpauley/vault,LolalyLuo/vault,skippy/vault,Banno/vault,mgk/vault,Aloomaio/vault,doodles526/vault,chrishoffman/vault,jgcallero/vault,jam-pot/vault,chrishoffman/vault,kingland/vault,hartsock/vault,ryon/vault,deverton/hashicorp-vault,jmhardison/vault,MonsantoCo/vault,mgk/vault,mymercurialsky/vault,memory/vault,jmhardison/vault,Banno/vault,naunga/vault,kingland/vault,naunga/vault,martin-ducar-gd/vault,mymercurialsky/vault,wjam/vault,hashicorp/vault,hashicorp/vault,rnaveiras/vault,wjam/vault,joelthompson/vault,quixoten/vault,rnaveiras/vault,quixoten/vault,kingland/vault,Caiyeon/vault,Aloomaio/vault,jmhardison/vault,kingland/vault,lirao/vault,jmhardison/vault,skippy/vault,hartsock/vault,michaelansel/vault,hartsock/vault,ryon/vault,hashicorp/vault,doodles526/vault,kingland/vault,rnaveiras/vault,michaelansel/vault,quixoten/vault,joelthompson/vault,rnaveiras/vault,Aloomaio/vault,mhurne/vault,joelthompson/vault,LolalyLuo/vault,mhurne/vault,martin-ducar-gd/vault,hashicorp/vault,Aloomaio/vault,MonsantoCo/vault,lirao/vault,quixoten/vault,mgk/vault,hashicorp/vault,joelthompson/vault,memory/vault,peteryhwong/vault,danielsomerfield/vault,hashicorp/vault