Make sure that all modules have description for inputs & outputs

[alexott]

trafficstars

Right now, some modules don't have description for inputs & outputs - it would be useful to add it, so they are rendered in TF registry

[hwang-db]

suggest to use https://github.com/terraform-docs/terraform-docs to auto-gen docs @yessawab so we have aligned formatting.

[alexott]

I'm not sure how much it will help here - we still need to have description field in the variables & outputs.