Docs: Webpack changes for addons

[jonniebigodes]

Closes #

What I did

With this pull request the Webpack documentation is updated to feature the newly created Webpack addons

What was done:

• Updated the documentation
• Created snippets
• Fixed some headings and callouts that were incorrectly rendered

@valentinpalkovic I've assigned you to this so that you can take a look at this and follow up with me on it so that we can adjust as needed if required. Let me know and we'll take it from there. Thanks in advance.

Checklist for Contributors

Testing

1. Follow the steps in the contributing instructions for this branch, docs_webpack_changes_for_addons.
2. Open the relevant documentation and verify the feature changes.

The changes in this PR are covered in the following automated tests:

• stories
• unit tests
• integration tests
• end-to-end tests

Manual testing

This section is mandatory for all contributions. If you believe no manual test is necessary, please state so explicitly. Thanks!

Documentation

• Add or update documentation reflecting your changes
• If you are deprecating/removing a feature, make sure to update
  MIGRATION.MD

Checklist for Maintainers

• When this PR is ready for testing, make sure to add ci:normal, ci:merged or ci:daily GH label to it to run a specific set of sandboxes. The particular set of sandboxes can be found in code/lib/cli/src/sandbox-templates.ts

• Make sure this PR contains one of the labels below:

  Available labels

  • bug: Internal changes that fixes incorrect behavior.
  • maintenance: User-facing maintenance tasks.
  • dependencies: Upgrading (sometimes downgrading) dependencies.
  • build: Internal-facing build tooling & test updates. Will not show up in release changelog.
  • cleanup: Minor cleanup style change. Will not show up in release changelog.
  • documentation: Documentation only changes. Will not show up in release changelog.
  • feature request: Introducing a new feature.
  • BREAKING CHANGE: Changes that break compatibility in some way with current major version.
  • other: Changes that don't fit in the above categories.

🦋 Canary release

This PR does not have a canary release associated. You can request a canary release of this pull request by mentioning the @storybookjs/core team here.

core team members can create a canary release here or locally with gh workflow run --repo storybookjs/storybook canary-release-pr.yml --field pr=<PR_NUMBER>

[kylegach]

LGTM!

[chantastic]

Approved, with a few suggestions on improving copy.

None of it is a show-stopper for me. But, given our wide range of readers, I felt that shorter, less conditional, sentences may improve readability.