Add specification on top-nav (#23)

content/en/specifications/specs.md

@@ -0,0 +1,31 @@
+---
+title: Specification
+linkTitle: Spec
+menu: { main: { weight: 35 } }
+cascade:
+  type: docs
+---
+
+The following specification versions are available:
+
+- [latest](https://theupdateframework.github.io/specification/latest/index.html)
+- [draft](https://theupdateframework.github.io/specification/draft/index.html)
+- [v1.0.33](https://theupdateframework.github.io/specification/v1.0.33/index.html)
+- [v1.0.32](https://theupdateframework.github.io/specification/v1.0.32/index.html)
+- [v1.0.31](https://theupdateframework.github.io/specification/v1.0.31/index.html)
+- [v1.0.30](https://theupdateframework.github.io/specification/v1.0.30/index.html)
+- [v1.0.29](https://theupdateframework.github.io/specification/v1.0.29/index.html)
+- [v1.0.28](https://theupdateframework.github.io/specification/v1.0.28/index.html)
+- [v1.0.27](https://theupdateframework.github.io/specification/v1.0.27/index.html)
+- [v1.0.26](https://theupdateframework.github.io/specification/v1.0.26/index.html)
+- [v1.0.25](https://theupdateframework.github.io/specification/v1.0.25/index.html)
+- [v1.0.24](https://theupdateframework.github.io/specification/v1.0.24/index.html)
+- [v1.0.23](https://theupdateframework.github.io/specification/v1.0.23/index.html)
+- [v1.0.22](https://theupdateframework.github.io/specification/v1.0.22/index.html)
+- [v1.0.20](https://theupdateframework.github.io/specification/v1.0.20/index.html)
+- [v1.0.19](https://theupdateframework.github.io/specification/v1.0.19/index.html)
+- [v1.0.18](https://theupdateframework.github.io/specification/v1.0.18/index.html)
+- [v1.0.17](https://theupdateframework.github.io/specification/v1.0.17/index.html)
+
+This list is also available from
+[Spec versions](https://theupdateframework.github.io/specification/).