make dropcap switchable between ascender/descender

src/content.config.ts

@@ -11,7 +11,7 @@ const posts = defineCollection({
         title: z.string(),
         date: z.date(),
         draft: z.boolean().default(false),
-        dropcap: z.boolean().default(true),
+        dropcap: z.enum(['ascender', 'descender']).default('descender'),
         toc: z.boolean().default(true),
     })
 });