Remove roadmap (#18568)

docs/docs/roadmap.mdx

@@ -1,26 +0,0 @@
----
-title: Roadmap
-hide_title: true
-sidebar_position: 8
----
-
-import useBaseUrl from "@docusaurus/useBaseUrl";
-
-## Roadmap
-
-You can find the approximate public roadmap for Superset [here](https://github.com/apache-superset/superset-roadmap/projects/1).
-
-<a href="https://github.com/apache-superset/superset-roadmap/projects/1">
-  <img
-    src={useBaseUrl("/img/roadmap.png")}
-    style={{
-      maxWidth: "100%",
-      boxShadow: "rgb(170, 170, 170) 0px 0px 3px 1px",
-    }}
-  />
-</a>
-
-Keep in mind that the roadmap represents only a subset of what's
-ahead. Many contributions come directly without ever making it onto the roadmap.
-Find out more about how the roadmap is managed in
-[SIP (Superset Improvement Proposal) 53](https://github.com/apache/superset/issues/10894)