feat: Add option for a noindex meta tag on the HTML index page

Adds a new config option `index_page_allow_indexing` which defaults to false.

Fixes: !1527

src/web/pages/index.rs

@@ -18,11 +18,13 @@ async fn index_handler(
 	struct Index<'a> {
 		server_name: &'a str,
 		first_run: bool,
+		allow_indexing: bool,
 	}
 
 	let template = Index {
 		server_name: services.globals.server_name().as_str(),
 		first_run: services.firstrun.is_first_run(),
+		allow_indexing: services.config.index_page_allow_indexing,
 	};
 	Ok(Html(template.render()?))
 }