Use .prettierrc consistently in docs (#15683)

Co-authored-by: fisker Cheung <lionkay@gmail.com>

docs/install.md

@@ -167,7 +167,7 @@ See [Pre-commit Hook](precommit.md) for more information.
 To summarize, we have learned to:
 
 - Install an exact version of Prettier locally in your project. This makes sure that everyone in the project gets the exact same version of Prettier. Even a patch release of Prettier can result in slightly different formatting, so you wouldn’t want different team members using different versions and formatting each other’s changes back and forth.
-- Add a `.prettierrc.json` to let your editor know that you are using Prettier.
+- Add a `.prettierrc` to let your editor know that you are using Prettier.
 - Add a `.prettierignore` to let your editor know which files _not_ to touch, as well as for being able to run `prettier --write .` to format the entire project (without mangling files you don’t want, or choking on generated files).
 - Run `prettier --check .` in CI to make sure that your project stays formatted.
 - Run Prettier from your editor for the best experience.