fix: separate description and preview

since description allows html tags, you may end up with escaped html
inside the embed preview description. add a separate config option

src/config.rs

@@ -55,6 +55,9 @@ pub struct ConfigTemplate {
 	#[serde_inline_default("you found my guestbook! please take a moment to sign it (:".into())]
 	pub description: String,
 
+	#[serde_inline_default("a simple guestbook to let visitors leave a mark".into())]
+	pub preview: String,
+
 	#[serde_inline_default("Kilroy was here  Ω".into())]
 	pub placeholder_body: String,
 

web/index.stpl

@@ -6,7 +6,7 @@
 	<meta name="viewport" content="width=device-width, initial-scale=1.0">
 	<meta property="og:type" content="website">
 	<meta property="og:title" content="<%= root.title %>">
-	<meta property="og:description" content="<%= root.description %>">
+	<meta property="og:description" content="<%= root.preview %>">
 	<style>
 	:root {
 		--bg-primary: <%= root.palette.bg_main %>;