Update Instructions to use our ACM Module

[osterman]

what

• Use terraform-aws-acm-request-certificate instead of aws cli

why

• 100% native terraform, no cli necessary

references

• https://github.com/cloudposse/terraform-aws-acm-request-certificate

[x80486]

Left a comment on issue 55. It has an almost complete example, except for the variables and so on. If the problem described can be fixed I can help with this one since it's almost the same text/code.

[nitrocode]

I see your issue comment here #55 (comment) which is helpful.

Here is a minimum example that we could add to the README PR #145