Enhanced and localized description

[tristanlins]

Currently there is only an english short description in the composer.json. We need the ability to define a complex description and localize it.

I would prefer to write docs in the repository, like:

README.de.md
README.de_DE.md
README.md

We could search for the language specific file, render it and show it in the backend.
The path/file could be configurable within the composer.json:

{
  "extra": {
    "contao": {
      "detailed-description": "README.{language}.md"
    }
  }
}

The pattern README.{language}.md could be the implicit default, an alternative pattern could be:

{
  "extra": {
    "contao": {
      "detailed-description": "docs/description.{language}.md"
    }
  }
}

As file formats we could support:

• *.md rendered as GFM
• *.rst rendered as standard reStructuredText (rendered with an online renderer or a PHP Library)
• *.html rendered as plain HTML
• *.txt rendered as plain text

We should also rethink about composer/composer#1954

[leofeyer]

+1

I'd prefer *.md, because we can render GFM via PHP in the back end.

[tristanlins]

Conflict with #41