Simplify README with better examples

[fjsj]

• Remove link to https://owais.lone.pw/blog/webpack-plus-reactjs-and-django/, it's an old post and there may be some stuff that doesn't apply anymore.
• The README should guide step-by-step how to configure a basic example. You may include the example code in the repo and point to it, but the step-by-step should have EVERYTHING that's needed to run the example, including Django's runserver and how to run webpack with the webpack-bundle-tracker.
• Explain entrypoint concept and how it's related to calling render_bundle .

"In webpack version < 4 it was common to add vendors as a separate entry point to compile it as a separate file (in combination with the CommonsChunkPlugin).
This is discouraged in webpack 4. Instead, the optimization.splitChunks option takes care of separating vendors and app modules and creating a separate file. Do not create an entry for vendors or other stuff that is not the starting point of execution."
Out of the box configs here: https://webpack.js.org/plugins/split-chunks-plugin/#defaults

• After the step-by-step is done, remove other sections that look like a step-by-step and make them look like references for configs.
• Make an opinionated guide on how to use hot-reload/hot-update locally. Include examples.
• Make an opinionated "How to use in Production". Tell what's the best way to do it (running it before collectstatic in the deploy script and NOT committing the bundle to the repo is probably the way to go, I think that's how django-react-boilerplate does it). Only quickly discuss after this the other ways to do it.
• Double-check everything and remove anything that's outdated.
• Add CSS preload option section (related to Add rel="preload" option for JS/CSS #203)
• Revamp webpack_static section
• How to keep render_bundle working in tests (see Unit tests fail because webpack-stats.json don't exists #187)
• Document new skip_common_chunks parameter in render_bundle (see Added skip_common_chunks argument to render_bundle to address duplicate script tags #296)

Also, after this is solved, we can probably close those issues:

• Outdated tutorial link in README.md? Outdated tutorial link in README.md? #275
• Utility function for uploading to static storage Utility function for uploading to static storage #279

[tintinmj]

Agree with this points. I came to this repo just to open a similar issue.