Add <link rel="alternate"> to header

I'm using this plugin for my site, but I was surprised to see that `` was not added to the header automatically.

Adding this to the header is trivial, but I would have expected to see this added automatically to aid in feed discovery.

Can a fix be added that automatically add the code below to the base.html.twig file?

```

```

Locate base.html.twig in the plugin's templates and inspect how the header is rendered. Add the requested RSS alternate link so generated pages include it for feed discovery, then verify the rendered header contains the URL and attributes shown in the issue.

Written by the indexing model from the issue text.