Fixed broken link in Quickstart page (#12516)

- **Description:** 
Corrected a specific link within the documentation.
  
  - **Issue:**
  #12490 

  - **Dependencies:**
  - **Tag maintainer:**
  - **Twitter handle:**

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Co-authored-by: Erick Friis <erick@langchain.dev>

docs/docs/get_started/quickstart.mdx

@@ -274,4 +274,4 @@ To continue on your journey:
 - Learn the other [key components](/docs/modules)
 - Read up on [LangChain Expression Language](/docs/expression_language) to learn how to chain these components together
 - Check out our [helpful guides](/docs/guides) for detailed walkthroughs on particular topics
-- Explore [end-to-end use cases](/docs/use_cases)
+- Explore [end-to-end use cases](/docs/use_cases/qa_structured/sql)