docs: remove monorepo ci footer (#9734)

There is no product page for this yet, remove it.

Author: jd

src/components/Footer/footer.ts

@@ -38,10 +38,6 @@ export const productCategory: Category = {
       text: 'Merge Queue',
       href: 'https://mergify.com/product/merge-queue',
     },
-    {
-      text: 'Monorepo CI',
-      href: 'https://mergify.com/product/monorepo-ci',
-    },
     {
       text: 'Merge Protections',
       href: 'https://mergify.com/product/merge-protections',