Clarify how maintainers can approve or reject a pull request

[nertzy]

Today the message from the bot just says “👍 or 👎”

I wish it told me more specifically what to do. I’ve seen people vote up and down the bot’s comment sometimes, and other times the PR itself. It would be great if the bot either supported both use cases or was more descriptive in where it will look.

[leonard-thieu]

@typescript-bot handles tagging of pull requests and does support both cases.