Updated Pinecone API Key Setup instructions for clarity

[DawgZter]

Minor improvement in sentence clarity for Pinecone setup instructions.

[DawgZter]

@Torantulino Let me know what else you need from me :)

[nponeccop]

Well, I think we can do better, especially that ChatGPT is good at improving the documentation. What we really need here is to add more details about how it works.

Pinecone is an SVM-like vector database that allows Auto-GPT to store chat history indexed by the vectors generated by the OpenAI text embeddings model, thus allowing Auto-GPT to "remember" past messages using a fuzzy match. This partially solves the problem of having a limited context memory.

I'm not saying this is much better (especially that I'm not confident in my grammar) but the original PR brings very little value IMO. Why the Pinecone is not optional? That isn't clear either.