Documentation urls should always include version number

[brospars]

Is your feature request related to a problem? Please describe.
Old blog or forum posts, stackoverflow that links to the ionic docs often point to the wrong version of the documentation.
Examples :

• https://ionicframework.com/blog/introducing-ionic-4-ionic-for-everyone/ the link to the Migration guide is https://ionicframework.com/docs/building/migration/ but should be https://ionicframework.com/docs/v4/building/migration/
• https://stackoverflow.com/a/55202668/2765126 the link to the css-custom-properties links to the current doc that includes more properties than in v4 so it's confusing

Describe the solution you'd like

• Always include the version number in the documentation urls (even the current version)
• If no version is added redirect to current version (to prevent dead links)

[piotr-cz]

I'm adding reference to ionic docs in the code.
Documentation for current version doesn't have it in it's URL and so as soon as new ionic version comes up, code is referencing docs for latest version (if URL still works) instead of version used in code base.

Examples:

• Nodejs docs
• Laravel docs are always using version number + master
  Additionally it redirects all visionless URLs to latest version (https://laravel.com/docs/database -> https://laravel.com/docs/10.x/database)