[add] editorconfig

.editorconfig

@@ -0,0 +1,27 @@
+# see https://EditorConfig.org
+
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+indent_size = tab
+indent_style = tab
+tab_width = 4
+insert_final_newline = true
+max_line_length = 80
+trim_trailing_whitespace = true
+curly_bracket_next_line = false
+indent_brace_style = K&R
+spaces_around_operators = true
+spaces_around_brackets = false
+quote_type = double
+
+[*.y{,a}ml{,lint}]
+indent_style = space
+indent_size = 2
+
+[*.md]
+indent_style = space
+indent_size = 2
+