chore(post-processor): update `vsphere-template`

[tenthirtyam]

Summary

• Updates error messages to use a more well-formed structure.
• Updates and simplifies code comments.
• Updates post-processor to generate documentation from structs.
• Generates the updated post-processor documentation.

Testing

packer-plugin-vsphere on  chore(post-processor)/update-vsphere-template [$!?] via 🐹 v1.22.1 
➜ make dev

packer-plugin-vsphere on  chore(post-processor)/update-vsphere-template [$!?] via 🐹 v1.22.1 
➜ make generate
2024/03/14 14:01:06 Copying "docs" to ".docs/"
2024/03/14 14:01:06 Replacing @include '...' calls in .docs/
Compiling MDX docs in '.docs' to Markdown in '.web-docs'...

packer-plugin-vsphere on  chore(post-processor)/update-vsphere-template [$!?] via 🐹 v1.22.1 took 11.6s 
➜ make build

packer-plugin-vsphere on  chore(post-processor)/update-vsphere-template [$!?] via 🐹 v1.22.1 took 3.2s 
➜ make test
?       github.com/hashicorp/packer-plugin-vsphere      [no test files]
?       github.com/hashicorp/packer-plugin-vsphere/builder/vsphere/common/testing       [no test files]
?       github.com/hashicorp/packer-plugin-vsphere/builder/vsphere/examples/driver      [no test files]
?       github.com/hashicorp/packer-plugin-vsphere/version      [no test files]
ok      github.com/hashicorp/packer-plugin-vsphere/builder/vsphere/clone        2.092s
ok      github.com/hashicorp/packer-plugin-vsphere/builder/vsphere/common       2.645s
ok      github.com/hashicorp/packer-plugin-vsphere/builder/vsphere/driver       6.430s
ok      github.com/hashicorp/packer-plugin-vsphere/builder/vsphere/iso  1.438s
ok      github.com/hashicorp/packer-plugin-vsphere/builder/vsphere/supervisor   4.679s
ok      github.com/hashicorp/packer-plugin-vsphere/post-processor/vsphere       1.781s
ok      github.com/hashicorp/packer-plugin-vsphere/post-processor/vsphere-template      2.089s