CONTRIBUTING.md: fix language, try two trailing spaces in markdown

The latter so I have easy place to copy it from when I need it, I mainly use Neovim+Kate which have native support and so does Kile

.editorconfig

@@ -0,0 +1,12 @@
+root = true
+
+[*]
+trim_trailing_whitespace = false
+insert_final_newline = true
+charset = utf-8
+indent_style = tab
+indent_size = tab
+
+[*.{yaml,yml,cff}]
+indent_style = space
+indent_size = 2

.gitattributes

@@ -0,0 +1 @@
+* text=auto

CONTRIBUTING.md

@@ -1,6 +1,11 @@
 Contributions are welcomed assuming my repositories are the correct place
 for it (the target is my repository or a PR I have open to another repository).
 
+In case [editorconfig](https://editorconfig.org/) isn't
+[natively supported by your editor of choice](https://editorconfig.org/#pre-installed),
+please consider [installing a plugin](https://editorconfig.org/#download).  
+E.g. VS Cod{e,ium} users can `CTRL-P` and execute `ext install EditorConfig.EditorConfig`.
+
 Issues being assigned to me doesn't matter, I use that just as a tool for
 rediscovering them easily, http://github.com/issues?q=is:open%20assignee:Mikaela