config: add .editorconfig

.editorconfig

@@ -0,0 +1,20 @@
+# Documentation available at editorconfig.org
+
+root=true
+
+[*]
+ident_style = space
+ident_size = 4
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+
+[*.rs]
+max_line_length = 100
+
+[*.md]
+trim_trailing_whitespace = false
+
+[*.yml]
+ident_size = 2