fix: add workflow_call trigger to terraform-docs workflow

- Add workflow_call to make it callable from master workflow
- Maintains existing pull_request and push triggers
- Resolves master workflow file validation failure
- Enables proper workflow orchestration

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: vjdhama

.github/workflows/terraform-docs.yaml

@@ -1,6 +1,7 @@
 name: Terraform Docs
 
 on:
+  workflow_call:
   pull_request:
   push:
     branches: