Fix .editorconfig trim_trailing_whitespace rule

.editorconfig

@@ -13,7 +13,7 @@ root = true
 end_of_line = lf # Unix-style newlines
 charset = utf-8 # All files are in UTF-8
 insert_final_newline = true # All files end with a newline
-trim_trailing_whitespaces = true
+trim_trailing_whitespace = true # No trailing whitespaces
 
 [Makefile]
 indent_style = tab