[CentOS-docs] wiki addition for AWS

[Warren Turkal]

My wiki name: WarrenTurkal

Page for addition: https://wiki.centos.org/Cloud/AWS

Proposed addition: I would like to add a column for the product code
for the CentOS images listed with AWS marketplace URLs. I use the
product code for "CENTOS-7 x86_64" to find the AMIs to start hosts
with that image in each region of AWS.

Thanks,
wt