Add Storybook global styling docs (#83)

We'd love to show you visual changes, but we don't have a build for the head (source) branch of this pull request.

Because this PR originates from a fork, it means we need a build for the fix-storybook-docs branch on the forked repository Dhanesh-GitH-account/design-system. Here's how you can create that build manually:

1. Create a build for storybookjs:master
2. In the repository forked under Dhanesh-GitH-account, add a remote named storybookjs if you haven't already, and fetch the upstream branch.

   HTTPSSSH

   git remote add storybookjs https://github.com/storybookjs/design-system.git

   You can list remotes with git remote -v

   git fetch storybookjs

   Using HTTPS with two-factor authentication requires a personal access token.
3. Merge storybookjs:master into Dhanesh-GitH-account:fix-storybook-docs

   git checkout fix-storybook-docs

   You may have to run git pull to update your local branch after switching.

   git merge storybookjs/master

   Don't forget to install or update dependencies after merging branches.
4. Finally, run a build for Dhanesh-GitH-account:fix-storybook-docs

   npx chromatic --project-token=0duof3ns9mts --branch-name="Dhanesh-GitH-account:fix-storybook-docs"

   Not sure how to create a build? Learn how to publish your Storybook