With this upgrade the Webpack internal config of Nullstack will be locally configurable.
And Purge no more will be ran by default in production.
We definitely need docs for that!

• It should (re)move the Purge part from styles doc and use as example.
• It should bring examples of real config (e.g. examples repo with plugins/loaders).
• The future NJS/NTS docs could link to here when "alternatively use extension like .tsx".