Clarified local provider usage (#8702)

Simplified instructions for the common use case of using a prebuilt terraform binary with a local provider binary

.github/CONTRIBUTING.md

@@ -75,39 +75,31 @@ resource.TestStep{
 
 ## Instructing terraform to use a local copy of the provider
 
-There are three different consumption strategies you can utilize
-
-* Using a local version of terraform
-
-  1. If you are building Terraform from source with a Google provider built from source, Terraform will automatically use the
-  local `terraform-provider-google` and `terraform-provider-google-beta` plugins in `$GOPATH/bin`.
-
-* Using a release version of terraform
-
 Note that these instructions apply to `0.13+`. For prior Terraform versions, look at past versions of this page for instructions.
 
-Before using a local provider version, you'll need to set up [0.13+'s expected directory structure](https://www.terraform.io/upgrade-guides/0-13.html#new-filesystem-layout-for-local-copies-of-providers).
+### Using released terraform binary with local provider binary
 
-You can set up the directories required with the following commands. You should substitute your system's architecture or a different path if desired:
-
-```
+Setup:
+```bash
 mkdir -p ~/.terraform.d/plugins/registry.terraform.io/hashicorp/google/5.0.0/darwin_amd64
 mkdir -p ~/.terraform.d/plugins/registry.terraform.io/hashicorp/google-beta/5.0.0/darwin_amd64
+ln -s $GOPATH/bin/terraform-provider-google ~/.terraform.d/plugins/registry.terraform.io/hashicorp/google/5.0.0/darwin_amd64/terraform-provider-google_v5.0.0
+ln -s $GOPATH/bin/terraform-provider-google-beta ~/.terraform.d/plugins/registry.terraform.io/hashicorp/google-beta/5.0.0/darwin_amd64/terraform-provider-google-beta_v5.0.0
 ```
 
+Once this setup is complete, terraform will automatically use the binaries generated by the `make build` commands in the `terraform-provider-google` and `terraform-provider-google-beta` repositories instead of downloading the latest versions. To undo this, you can run:
+
+```bash
+rm -rf ~/.terraform.d/plugins/registry.terraform.io/hashicorp/
+```
+
+For more information, check out Hashicorp's documentation on the [0.13+ filesystem layout](https://www.terraform.io/upgrade-guides/0-13.html#new-filesystem-layout-for-local-copies-of-providers).
+
 If multiple versions are available in a plugin directory (for example after `terraform providers mirror` is used), Terraform will pick the most up-to-date provider version within version constraints. As such, we recommend using a version that is several major versions ahead for your local copy of the provider, such as `5.0.0`.
 
-  2. When you run `terraform init` supply the local binary registry location using the [-plugin-dir](https://www.terraform.io/docs/commands/init.html#plugin-dir-path) parameter. ie `terraform init -plugin-dir=$GOPATH/.terraform` with the provider located at`$GOPATH/.terraform/registry.terraform.io/hashicorp/google/5.0.0/darwin_amd64/terraform-provider-google_v5.0.0`
-      * note: terraform will not download additional providers remotely. All requested providers should be in the -plugin-dir
-      * note: each time you rebuild the binary you will have to rerun `terraform init -plugin-dir=<your-binary-registry-location>` as the hash is invalidated.
-  3. Use the [provider discovery directory](https://www.terraform.io/docs/extend/how-terraform-works.html#discovery) at `~/.terraform.d/plugins`. Terraform will attempt to use the provider binaries here.
-      * note: if a provider is managed in the discovery directory, Terraform will not pull it from the registry. `terraform providers mirror ~/.terraform.d/plugins` will mirror any versions required by the current config into the discovery directory from the registry.
-      * note: you can either copy the provider binary to this location or do a symlink to the build output
-        ```bash
-        # this symlink keeps the fake 5.0.0 version up-to-date with `make build`'s output automatically
-        ln -s $GOPATH/bin/terraform-provider-google ~/.terraform.d/plugins/registry.terraform.io/hashicorp/google/5.0.0/darwin_amd64/terraform-provider-google_v5.0.0
-        ln -s $GOPATH/bin/terraform-provider-google-beta ~/.terraform.d/plugins/registry.terraform.io/hashicorp/google-beta/5.0.0/darwin_amd64/terraform-provider-google-beta_v5.0.0
-        ```
+### Building terraform binary from source
+
+If you build the terraform binary from source, it will automatically use the binaries generated by the `make build` commands in the `terraform-provider-google` and `terraform-provider-google-beta` repositories instead of downloading the latest versions.
 
 ### FAQ