Document the removal of config options from 4.13 -> 5.x

[zoglo]

TL;DR - url_suffix, legacy_routing or similar when updating

People are repeatedly asking the same question on the community forums (sometimes by the same person), that they can not update because of a long error message including:

  Unrecognized option "url_suffix" under "contao". Available options are "bac  
  kend", "backup", "console_path", "crawl", "cron", "csp", "csrf_cookie_prefi  
  x", "csrf_token_name", "editable_files", "error_level", "image", "insert_ta  
  gs", "intl", "localconfig", "locales", "mailer", "messenger", "pretty_error  
  _screens", "preview_script", "sanitizer", "search", "security", "upload_pat  
  h".  

Either I am missing the part where configuration options have been removed (unless they are on specific pages as a hint) but it may help if that could be documented on this page
https://docs.contao.org/manual/de/migration/#contao-4-13-auf-5-x

Opening the issue since I am unsure if that is the right place or not

[fritzmg]

Mentioning that you might have to remove some config options when updating from Contao 4 to 5 should definitely be done in the migration article.

The config article needs to have two (or more) tabs for the config options.

[zoglo]

The config article needs to have two (or more) tabs for the config options.

Would be a separate issue / not part of this one but can you tell me what you are referring to on https://docs.contao.org/dev/reference/config/?

[fritzmg]

The tabs here:

• https://docs.contao.org/manual/en/system/settings/#config-yaml
• https://docs.contao.org/dev/reference/config/

They already exist (but might need to be updated).

[zoglo]

Don't mind assigning me to this issue then :)