Add stewardship readiness asset: .editorconfig

.editorconfig

@@ -0,0 +1,17 @@
+# EditorConfig is awesome: https://editorconfig.org
+<!-- stewardship-standard: editorconfig-v1 -->
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+insert_final_newline = true
+indent_style = space
+indent_size = 2
+trim_trailing_whitespace = true
+
+[*.{md,markdown}]
+trim_trailing_whitespace = false
+
+[Makefile]
+indent_style = tab