Correct link for newsletters on newsletter page

Author: rfay

src/pages/newsletter.astro

@@ -21,7 +21,7 @@ const title = `Newsletter`
     <div class="prose dark:prose-invert my-8">
     This is a low-volume newsletter, usually just once a month. We'd love to be able to keep in touch with you.
 
-      <a href="/blog/category/newsletter">See previous newsletters</a>.
+      <a href="/blog/category/newsletters">See previous newsletters</a>.
     </div>
     <!-- NEW FORM GOES BELOW HERE -->