[INFERENCE PROVIDERS] guide on structured output (#1824)

* first draft of guide on structured output

* add to toc

* fix toc link

* more fixing

* Apply suggestions from code review

Co-authored-by: Steven Liu <[email protected]>

* remove python / json tabs

* spelling

* tab placement

---------

Co-authored-by: Steven Liu <[email protected]>

Author: burtenshaw

docs/inference-providers/_toctree.yml

@@ -17,6 +17,8 @@
     title: Your First API Call
   - local: guides/building-first-app
     title: Building Your First AI App
+  - local: guides/structured-output
+    title: Structured Outputs with LLMs
 
 - title: Providers
   sections: