New Extension : Calendar (#1052)

* Add link to docs

* Divide image size by 2

docs/extensions.html

@@ -3,6 +3,11 @@ title: Extensions
 layout: default
 route: extensions
 extensions:
+- name: bulma-calendar
+  url: https://github.com/Wikiki/bulma-calendar
+  slug: bulma-calendar
+  width: 382
+  height: 338
 - name: bulma-pageloader
   url: https://github.com/Wikiki/bulma-pageloader
   slug: bulma-pageloader