Update README.md

PR Comment is a big plus to why we opt to use Terraform Github actions. Updated the readme file so that everyone will understand how to take advantage of the terraform concise on PR comment capability

README.md

@@ -105,6 +105,59 @@ steps:
         body: output
       })
 ```
+Specify terraform working directory and previous outputs can be used in subsequent steps for a concise comment on the pull request
+```yaml
+env:
+    tf_actions_working_dir: <Terraform working directory>
+steps:
+- uses: actions/checkout@v2
+- uses: hashicorp/setup-terraform@v1
+
+- name: Terraform fmt
+  id: fmt
+  run: cd ${{ env.tf_actions_working_dir }} && terraform fmt
+  continue-on-error: true
+
+- name: Terraform Init
+  id: init
+  run: cd ${{ env.tf_actions_working_dir }} && terraform init
+
+- name: Terraform Validate
+  id: validate
+  run: cd ${{ env.tf_actions_working_dir }} && terraform validate -no-color
+
+- name: Terraform Plan
+  id: plan
+  run: cd ${{ env.tf_actions_working_dir }} && terraform plan -no-color
+  continue-on-error: true
+
+- uses: actions/github-script@0.9.0
+  if: github.event_name == 'pull_request'
+  env:
+    PLAN: "terraform\n${{ steps.plan.outputs.stdout }}"
+  with:
+    github-token: ${{ secrets.GITHUB_TOKEN }}
+    script: |
+      const output = `#### Terraform Format and Style 🖌\`${{ steps.fmt.outcome }}\`
+      #### Terraform Initialization ⚙️\`${{ steps.init.outcome }}\`
+      #### Terraform Validation 🤖${{ steps.validate.outputs.stdout }}
+      #### Terraform Plan 📖\`${{ steps.plan.outcome }}\`
+      
+      <details><summary>Show Plan</summary>
+      
+      \`\`\`${process.env.PLAN}\`\`\`
+      
+      </details>
+      
+      *Pusher: @${{ github.actor }}, Action: \`${{ github.event_name }}\`, Working Directory: \`${{ env.tf_actions_working_dir }}\`, Workflow: \`${{ github.workflow }}\`*`;
+        
+      github.issues.createComment({
+        issue_number: context.issue.number,
+        owner: context.repo.owner,
+        repo: context.repo.repo,
+        body: output
+      })
+```
 
 ## Inputs