fix: duplicate text in typescript rag documentation (#1275)

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

## Type of change

**Type:** Fix typo/bug/link/formatting

## Related issues/PRs


To automatically close an issue when this PR is merged, use closing
keywords:
- Fixes: #1274

## 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
- (Internal team members only / optional) I have created a preview
deployment using the [Create Preview Branch
workflow](https://github.com/langchain-ai/docs/actions/workflows/create-preview-branch.yml)

## Additional notes
<!-- Any other information that would be helpful for reviewers -->

Author: anoopw3bdev

src/oss/langchain/rag.mdx

@@ -561,7 +561,6 @@ agent = create_agent(model, tools, system_prompt=prompt)
 :::
 :::js
 
-Given our tool, we can construct the agent:
 
 ```typescript
 import { createAgent } from "langchain";