Upgrades docusaurus (#2039)

Summary:
**Summary**

Runs `yarn upgrade docusaurus` to ensure we're on the latest set of dependencies

**Test Plan**

Run the docusaurus build and test the website on http://localhost:3000/

```
cd website
yarn run build
yarn run start
```
Pull Request resolved: #2039

Reviewed By: mrkev

Differential Revision: D14539917

Pulled By: mrkev

fbshipit-source-id: 16f79868bbae7e78076df26997021b13b097d66d

Author: Claudio Procida