Update guideline ordering and align with public modules

Reordering is mostly based on having all repo-level guidelines together and then dive into the actual content/resources.

This includes addition of repo naming guidelines, more clarification around the expected files, and an update to the sample readme to add type, default, and required values for inputs. Most suggestions reflect what HashiCorp recommends/requires when using public registries. One of the big advantages with consistent naming is easier discoverability, but maybe open the door for us to scan the repos and build our own registry-like site for others to scan (rather than going to GitLab directly).

Reference documents:

• https://www.terraform.io/docs/registry/modules/publish.html#requirements
• https://www.terraform.io/docs/modules/index.html#standard-module-structure

And one thing to note/make clear... the Terraform recommendations use the pattern terraform-<PROVIDER>-<NAME>, but I decided to drop terraform- from the beginning. They do this to make it easier to scan your GitHub repos and find eligible modules. But, in our case, they are already in a subgroup, so all modules (minus this repo) are TF modules.

After merging, we will update the existing repos to use the recommended naming patterns, requiring coordination amongst those already using/experimenting with the modules.

LGTM

merged

mentioned in commit 56b1ee36