Generate readme for submodules @goruha (#167)
## what * Generate readme for submoduleswhy
- Allow all to keep the README updated
references
🐛 Bug Fixes
fix: wire `ipv6_cidr_block_network_border_group` to module and fix tflint findings @RoseSecurity (#171)
## what- Wire the existing
ipv6_cidr_block_network_border_groupinput into the VPC resource and replace legacy splat expressions in outputs with modern full-splat syntax.
what
- This allows callers to restrict advertisement of AWS-generated IPv6 addresses to a specific network border group (such as a Local Zone). The output syntax update keeps the module aligned with current Terraform conventions without changing output behavior.