Editorconfig : Add per-file configs.

.editorconfig

@@ -1,6 +1,19 @@
 [*]
-end_of_line = lf
-charset = utf-8
+end_of_line  = lf
+charset      = utf-8
 indent_style = tab
-insert_final_newline = true
+indent_size  = 2
+insert_final_newline     = true
 trim_trailing_whitespace = true
+
+[Makefile]
+indent_size = 2
+
+[*.{nix,js}]
+indent_size = 2
+
+[*.lua]
+indent_size = 4
+
+[*.{sh,md}]
+indent_size = 8