Add guide page to docs

[dcastil]

I've seen a "guide" or "usage" page in docs often.

• https://vuejs.org/guide/introduction.html
• https://redux.js.org/usage/
• https://prettier.io/docs/en/install.html
• https://code.visualstudio.com/docs/editor/codebasics
• https://tanstack.com/query/v3/docs/react/guides/important-defaults

People recognize what that means and the "recipes" pages is a bit similar. I should create a "guide" page and integrate the "recipes" page into it. Ideally I'd warn that the recipes page will move to the guide page in a release and move the page in another release.

[dcastil]

I could also add installation instructions to the guide page which was requested in #232.

[dcastil]

Possible things to explain in guide:

• How to install library
• How to set up tailwind-merge in general
• How to set up extended scales in Tailwind config
  • Custom classes getting removed #315
  • Identify Tailwind custom classes #302
  • twMerge is removing custom classes wrongly #276
  • custom `boxShadow` being deleted from `className` when color is specified #275
  • Custom extended colors (in text) override custom extended FontSize #274
• How to set up plugins and classes added to Tailwind
  • Extend config with new class name from plugin #322
  • text-balance incompatibility  #321
  • Can not override class with custom class in tailwind-merge #207
  • Add recommendation from to prefer variables over aggregate helper classes How to merge custom utility classes (which change multiple properties)? #323 (comment)
• Incorporate recipes docs into guide