fix: multiple network error msg

[tenthirtyam]

Summary

• Updates the error messages when more than one network with the same name resolves to more than one network.
• Updated the documentation for network in vsphere-iso and vsphere-clone builders.

Testing

➜  packer-plugin-vsphere git:(fix/multiple-network-error-msg) ✗ go fmt builder/vsphere/driver/vm.go
➜  packer-plugin-vsphere git:(fix/multiple-network-error-msg) ✗ go fmt builder/vsphere/driver/network.go 
➜  packer-plugin-vsphere git:(fix/multiple-network-error-msg) ✗ go fmt builder/vsphere/iso/step_create.go
➜  packer-plugin-vsphere git:(fix/multiple-network-error-msg) ✗ go fmt builder/vsphere/clone/step_clone.go
➜  packer-plugin-vsphere git:(fix/multiple-network-error-msg) ✗ make generate
2024/04/25 22:52:24 Copying "docs" to ".docs/"
2024/04/25 22:52:24 Replacing @include '...' calls in .docs/
Compiling MDX docs in '.docs' to Markdown in '.web-docs'...
➜  packer-plugin-vsphere git:(fix/multiple-network-error-msg) ✗ make build
➜  packer-plugin-vsphere git:(fix/multiple-network-error-msg) ✗ 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        2.117s
ok      github.com/hashicorp/packer-plugin-vsphere/builder/vsphere/common       4.388s
ok      github.com/hashicorp/packer-plugin-vsphere/builder/vsphere/driver       6.576s
ok      github.com/hashicorp/packer-plugin-vsphere/builder/vsphere/iso  4.647s
ok      github.com/hashicorp/packer-plugin-vsphere/builder/vsphere/supervisor   7.780s
ok      github.com/hashicorp/packer-plugin-vsphere/post-processor/vsphere       3.234s
ok      github.com/hashicorp/packer-plugin-vsphere/post-processor/vsphere-template      4.134s

Reference

Ref: #237