fix use of --type-add

README.md

@@ -217,7 +217,7 @@ To see a list of types supported, run `rg --type-list`. To add a new type, use
 `--type-add`:
 
 ```
-$ rg --type-add 'foo:*.foo,*.foobar'
+$ rg --type-add 'foo:*.{foo,foobar}'
 ```
 
 The type `foo` will now match any file ending with the `.foo` or `.foobar`