Add formatting instructions to docs contribution (google#723)

I just realized that our contributing to docs instructions is circular
(CONTRIBUTING.md points to docs/README.md which points back to
CONTRIBUTING.md). I removed that line and added in the formatting
instructions.

---------

Co-authored-by: Hayley Denbraver <denbraver@google.com>

docs/README.md

@@ -11,9 +11,19 @@ Here are other [pre-requisites] and instructions for running the [docs locally].
 [pre-requisites]: https://docs.github.com/en/pages/setting-up-a-github-pages-site-with-jekyll/testing-your-github-pages-site-locally-with-jekyll#prerequisites
 [docs locally]: https://docs.github.com/en/pages/setting-up-a-github-pages-site-with-jekyll/testing-your-github-pages-site-locally-with-jekyll#building-your-site-locally
 
-## Contributing to the docs
+## Formatting docs
 
-Please see [CONTRIBUTING.md](https://github.com/google/osv-scanner/blob/main/CONTRIBUTING.md/#contributing-documentation) for information on contributing documentation.
+We use - [Prettier](https://prettier.io/) to standardize the format of markdown and config files.
+
+This requires [node/npm](https://docs.npmjs.com/downloading-and-installing-node-js-and-npm) to be installed.
+
+### Running the formatter
+
+Run the following in the project directory:
+
+```shell
+./scripts/run_formatters.sh
+```
 
 ## Documentation theme