Show seed policy and scope in "online" button

src/components/ScopePolicyExplainer.svelte

@@ -0,0 +1,17 @@
+<script lang="ts">
+  import type { Scope, Policy } from "@httpd-client";
+
+  export let scope: Scope;
+  export let policy: Policy;
+</script>
+
+{#if policy === "allow"}
+  All discovered repositories will get seeded,
+{:else if policy === "block"}
+  Only repositories marked as such will get seeded,
+{/if}
+{#if scope === "all"}
+  and all changes in those repos, made by any peer, will be synced.
+{:else if scope === "followed"}
+  and only changes made by explicitly followed peers will be synced.
+{/if}