treewide: editorconfig fixes

- remove trailing whitespace
- use spaces for indentation

pkgs/development/tools/documentation/mkdocs/default.nix

@@ -41,7 +41,7 @@ buildPythonApplication rec {
       MkDocs is a fast, simple and downright gorgeous static site generator that's
       geared towards building project documentation. Documentation source files
       are written in Markdown, and configured with a single YAML configuration file.
-      
+
       MkDocs can also be used to generate general-purpose Websites.
     '';
     homepage = "http://mkdocs.org/";