Improve doc about JS build / add more watch scripts

[igorschoester]

Context

Summary

This PR can be summarized in the following changelog entry:

• Improves our documentation a bit.

Relevant technical choices:

• Add watch commands in the packages that support it
• Fix URL to Free repo
  Note: the CSS watch in components is not how we use the CSS at all
  Note: I skipped a JSON watch of the style-guide, deprecated package anyway

Test instructions

Test instructions for the acceptance test before the PR gets merged

This PR can be acceptance tested by following these steps:

• Does the documentation make sense?
• Does everything still work?
• Do the new commands work?

Relevant test scenarios

• Changes should be tested with the browser console open
• Changes should be tested on different posts/pages/taxonomies/custom post types/custom taxonomies
• Changes should be tested on different editors (Default Block/Gutenberg/Classic/Elementor/other)
• Changes should be tested on different browsers
• Changes should be tested on multisite

Test instructions for QA when the code is in the RC

• QA should use the same steps as above.

QA can test this PR by following these steps:

• Tooling/readme

Impact check

This PR affects the following parts of the plugin, which may require extra testing:

UI changes

• This PR changes the UI in the plugin. I have added the 'UI change' label to this PR.

Other environments

• This PR also affects Shopify. I have added a changelog entry starting with [shopify-seo], added test instructions for Shopify and attached the Shopify label to this PR.

Documentation

• I have written documentation for this change. For example, comments in the Relevant technical choices, comments in the code, documentation on Confluence / shared Google Drive / Yoast developer portal, or other.

Quality assurance

• I have tested this code to the best of my abilities.
• During testing, I had activated all plugins that Yoast SEO provides integrations for.
• I have added unit tests to verify the code works as intended.
• If any part of the code is behind a feature flag, my test instructions also cover cases where the feature flag is switched off.
• I have written this PR in accordance with my team's definition of done.
• I have checked that the base branch is correctly set.

Innovation

• No innovation project is applicable for this PR.
• This PR falls under an innovation project. I have attached the innovation label.
• I have added my hours to the WBSO document.

Fixes #

[github-actions]

@igorschoester Please be aware that following packages have been abandoned and are not actively maintained anymore:

Package name	Path
@yoast/babel-preset	packages/babel-preset
@yoast/components	packages/components
@yoast/e2e-tests	packages/e2e-tests
@yoast/helpers	packages/helpers
@yoast/jest-preset	packages/jest-preset
@yoast/style-guide	packages/style-guide
eslint-config-yoast	packages/esling-config-yoast

Please consider using the other packages instead.

[thijsoo]

CR + ACC 👍