update chatapi port number instructions

### Please verify the following:

- [x] You have searched for relevant keywords in [recent open and closed issues](https://github.com/open-learning-exchange/open-learning-exchange.github.io/issues?q=is%3Aissue) to avoid duplicates.

### Problem

Update development instructions to match chatapi port change

### Screenshot (when necessary)

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### Proposed solution(s)

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