Consider Warning/Error With Mismatched Terraform Architecture

Seems like right now tfplugindocs generate got hardcoded - plugins/registry.terraform.io/hashicorp/ for the providerPath, but in case of locally developed provider it's not a case.

```
$ tfplugindocs generate
rendering website for provider "terraform-provider-xxx" (as "terraform-provider-xxx")
exporting schema from Terraform
compiling provider "xxx"
using Terraform CLI binary from PATH if available, otherwise downloading latest Terraform CLI binary
running terraform init
Error executing command: unable to generate website: exit status 1

Error: Incompatible provider version

Provider registry.terraform.io/hashicorp/xxx v0.0.1 does not have a
package available for your current platform, windows_386.

Provider releases are separate from Terraform CLI releases, so not all
providers are available for all platforms. Other versions of this provider
may have different platforms supported.
```