fix(demo): add social graph preview image

Author: tomastrajan

projects/elements-demo/src/assets/social-preview.png

@@ -14,7 +14,7 @@
     />
     <meta
       property="og:image"
-      content="https://angular-extensions.github.io/elements/assets/logo/logo.svg"
+      content="https://angular-extensions.github.io/elements/assets/social-preview.png"
     />
     <meta
       property="og:url"