Add .editorconfig

.editorconfig

@@ -0,0 +1,26 @@
+# .editorconfig https://editorconfig.org/#example-file
+# synthesized from https://github.com/rust-lang/rust/blob/master/.editorconfig and my chatgpt overlord
+
+root = true
+
+[*]
+indent_style = space
+indent_size = 4
+trim_trailing_whitespace = true
+insert_final_newline = true
+charset = utf-8
+end_of_line = lf
+
+[*.rs]
+max_line_length = 100
+
+[*.md]
+# double whitespace at end of line
+# denotes a line break in Markdown
+trim_trailing_whitespace = false
+
+[*.{yml,yaml}]
+indent_size = 2
+
+[Makefile]
+indent_style = tab