Add Tfplugindocs workflow file (hashicorp#2556)

.github/workflows/documentation-check.yaml

@@ -0,0 +1,42 @@
+name: "Documentation Updates"
+
+on:
+    pull_request:
+      paths:
+        - 'docs/**'
+      types: [opened, synchronize, labeled]       
+
+    push:
+      branches:
+        - main
+
+jobs:
+    check-docs:
+      runs-on: ubuntu-latest
+
+      if: ${{ !contains(github.event.pull_request.labels.*.name, 'no-documentation') }}
+
+      steps:
+        - name: Checkout repository
+          uses: actions/checkout@0ad4b8fadaa221de15dcec353f45205ec38ea70b # v4.1.4
+
+        - name: Set up Go
+          uses: actions/setup-go@0c52d547c9bc32b1aa3301fd7a9cb496313a4491 # v5.0.0
+          with:
+            go-version-file: 'go.mod'
+
+        - name: Install tfplugindocs command
+          run: go install github.com/hashicorp/terraform-plugin-docs/cmd/tfplugindocs@latest
+
+        - name: Run tfplugindocs command
+          run: tfplugindocs generate
+
+        - name: Check for changes
+          run: |
+            git diff --exit-code
+  
+        - name: Undocumented changes 
+          run: |
+            echo "Documentation is not up to date. Please refer to the `Making Changes` in the Contribution Guide on how to properly update documentation."
+            exit 1
+          if: failure()