Changing @cloudflare/textsplitters to @langchain/textsplitters correct package name (#20435)

I think the package we meant to reference here is the @langchain/textsplitters. @cloudflare/textsplitters doesn't seem to exist: https://www.npmjs.com/search?q=@cloudflare/textsplitters

Author: aninibread

src/content/docs/workers-ai/tutorials/build-a-retrieval-augmented-generation-ai.mdx

@@ -492,7 +492,7 @@ For large pieces of text, it is recommended to split the text into smaller chunk
 To implement this, we'll add a new NPM package to our project, `@langchain/textsplitters':
 
 ```sh
-npm install @cloudflare/textsplitters
+npm install @langchain/textsplitters
 ```
 
 The `RecursiveCharacterTextSplitter` class provided by this package will split the text into smaller chunks. It can be customized to your liking, but the default config works in most cases:
@@ -591,4 +591,4 @@ To do more:
 - Explore [Examples](/workers/examples/) to experiment with copy and paste Worker code.
 - Understand how Workers works in [Reference](/workers/reference/).
 - Learn about Workers features and functionality in [Platform](/workers/platform/).
-- Set up [Wrangler](/workers/wrangler/install-and-update/) to programmatically create, test, and deploy your Worker projects.
+- Set up [Wrangler](/workers/wrangler/install-and-update/) to programmatically create, test, and deploy your Worker projects.