Update README.md example to fix escaping issues.

Sometimes (on later versions of terraform) terraform will output warnings regarding templating which include the ${} pattern. In a template, the contents are interpreted as js which will almost always fail.

README.md

@@ -113,14 +113,24 @@ steps:
   with:
     github-token: ${{ secrets.GITHUB_TOKEN }}
     script: |
+      const validate = ${{ toJson(steps.validate.outputs.stdout) }};
+      const plan = ${{ toJson(steps.plan.outputs.stdout) }};
+
       const output = `#### Terraform Format and Style 🖌\`${{ steps.fmt.outcome }}\`
       #### Terraform Initialization ⚙️\`${{ steps.init.outcome }}\`
-      #### Terraform Validation 🤖${{ steps.validate.outputs.stdout }}
+      #### Terraform Validation 🤖\`${{ steps.validate.outcome }}\`
+
+      <details><summary>Show Validation</summary>
+
+      \`\`\`${validate}\`\`\`
+
+      </details>
+
       #### Terraform Plan 📖\`${{ steps.plan.outcome }}\`
 
       <details><summary>Show Plan</summary>
 
-      \`\`\`${process.env.PLAN}\`\`\`
+      \`\`\`terraform\n${plan}\`\`\`
 
       </details>