docs: product roadmap and zitadel versions (#9838)

# Which Problems Are Solved

The current public roadmap can be hard to understand for customers and
it doesn't show the timelines for the different versions. which results
in a lot of requests.
It only outlines what is already fixed on the timeline, but doesn't give
any possibilities to outline future topics / features, which not yet
have a timeline

# How the Problems Are Solved

A new roadmap page is added
- Outline for each version when it will have which state
- Outline different zitadel versions with its features, deprecations,
breaking changes, etc.
- Show future topics, which are not yet on the roadmap

docs/sidebars.js

@@ -183,7 +183,6 @@ module.exports = {
           items: [
             "guides/manage/user/reg-create-user",
             "guides/manage/customize/user-metadata",
-            "guides/manage/customize/user-schema",
             "guides/manage/user/scim2",
           ],
         },
@@ -611,6 +610,20 @@ module.exports = {
         },
       ],
     },
+    {
+      type: "category",
+      label: "Product Information",
+      collapsed: true,
+      items: [
+        "product/roadmap",
+        "product/release-cycle",
+        {
+          type: "link",
+          label: "Changelog",
+          href: "https://zitadel.com/changelog",
+        },
+      ],
+    },
     {
       type: "category",
       label: "Support",