Specify command to run Prettier (Qiskit#1245)

Clarify the options for fixing a file with a Prettier error.

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Co-authored-by: Eric Arellano <14852634+Eric-Arellano@users.noreply.github.com>

README.md

@@ -308,9 +308,9 @@ You can also check that API docs and translations render by using any of these a
 
 CI will check on every PR that any changed files render correctly. We also run a weekly cron job to check that every page renders correctly.
 
-## Format TypeScript files
+## Format README and TypeScript files
 
-If you're working on our support code in `scripts/`, run `npm run fmt` to automatically format the files.
+Run `npm run fmt` to automatically format the README, `.github` folder, and `scripts/` folder. You should run this command if you get the error in CI `run Prettier to fix`.
 
 To check that formatting is valid without actually making changes, run `npm run check:fmt` or `npm run check`.