change product dropdown (#895)

## Overview
<!-- Brief description of what documentation is being added/updated -->

## Type of change

**Type:** [Replace with: New documentation page / Update existing
documentation / Fix typo/bug/link/formatting / Remove outdated content /
Other]

## Related issues/PRs
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## Checklist
<!-- Put an 'x' in all boxes that apply -->
- [ ] I have read the [contributing guidelines](README.md)
- [ ] I have tested my changes locally using `docs dev`
- [ ] All code examples have been tested and work correctly
- [ ] I have used **root relative** paths for internal links
- [ ] I have updated navigation in `src/docs.json` if needed
- I have gotten approval from the relevant reviewers
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deployment using the [Create Preview Branch
workflow](https://github.com/langchain-ai/docs/actions/workflows/create-preview-branch.yml)

## Additional notes
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Author: lnhsingh

src/docs.json

@@ -129,9 +129,9 @@
         ]
       },
       {
-        "product": "OSS",
+        "product": "LangChain + LangGraph",
         "icon": "link",
-        "description": "LangChain and LangGraph",
+        "description": "Open source frameworks",
         "dropdowns": [
           {
             "dropdown": "Python",