New extensions : Pageloader & Ribbon (#918)

* New extensions

Add links to the following extensions:
- pageloader
- Ribbon

* Revert "New extensions"

This reverts commit 3f6fbc664f6fa0b04e5e244cce8b39db135228f2.

* Add images of new extensions

* Update extensions.html

docs/extensions.html

@@ -2,6 +2,16 @@
 layout: default
 route: extensions
 extensions:
+- name: bulma-pageloader
+  url: https://github.com/Wikiki/bulma-pageloader
+  slug: bulma-pageloader
+  width: 490
+  height: 278
+- name: bulma-ribbon
+  url: https://github.com/Wikiki/bulma-ribbon
+  slug: bulma-ribbon
+  width: 646
+  height: 174
 - name: bulma-badge
   url: https://github.com/Wikiki/bulma-badge
   slug: bulma-badge