Previously, there were discussions on how to write certain plurals. So, we explicitly document the special plurals to end the discussion.
Add `markdownlint` linter and fix issues. Config is based on the one from electron's repo with a few rules relaxed.
* Add german translation guidelines * Add German Language to Docs * add Translation cateory & move guidelines into it Co-authored-by: kolaente <k@knt.li> Co-authored-by: 6543 <6543@obermui.de>
