add meta tag for CEM

docs/index.html

@@ -12,6 +12,7 @@
       name="viewport"
       content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0"
     />
+    <meta name="custom-elements-manifest" content="dist/custom-elements.json" />
     <meta property="og:title" content="Shoelace" />
     <meta
       property="og:description"
@@ -20,7 +21,6 @@
     <meta property="og:type" content="website" />
     <meta property="og:url" content="https://shoelace.style/" />
     <meta property="og:image" content="https://shoelace.style/assets/images/og-image.png" />
-
     <meta name="twitter:card" content="summary_large_image" />
     <meta name="twitter:site" content="@shoelace_style" />
     <meta name="twitter:creator" content="@claviska" />