categorise first column of docs into 3 groups

Signed-off-by: clux <sszynrae@gmail.com>

docs/kubernetes-version.md

@@ -1,3 +1,4 @@
+# Kubernetes Version
 
 ## Policy
 

docs/stability.md

@@ -9,7 +9,7 @@ Our support level is determined by our continuous integration.
 
 [Github Actions](https://github.com/kube-rs/kube/actions/workflows/ci.yml) continually builds and tests `kube` against the [LTS supported environments](https://github.com/actions/virtual-environments#available-environments) for **Ubuntu**, and **macOS**, and **Windows**:
 
-| Support                        | Source         | Guarantee        | LTS Cycle  |
+| Support                        | Source         | Guarantee        | Upstream Policy |
 | ------------------------------ | -------------- | ---------------- | ---------- |
 | :material-check-all: supported | Linux          | `ubuntu-latest`  | [2 years](https://ubuntu.com/about/release-cycle)    |
 | :material-check-all: supported | Windows        | `windows-latest` | [3 years](https://docs.microsoft.com/en-us/windows-server/get-started/windows-server-release-info)    |

mkdocs.yml

@@ -47,21 +47,23 @@ theme:
 # mkdocs serve will tell us about uncovered documents or broken links
 nav:
 - Information:
-  #- index.md
-  - getting-started.md
-  #- quick-tutorial.md
-  - changelog.md
-  - security.md
-  - release-process.md
-  - rust-version.md
-  - kubernetes-version.md
-  - stability.md
-  - architecture.md
-  - troubleshooting.md
-  - adopters.md
-  - guides.md
-  - upgrading.md
-  - features.md
+    Usage:
+    #- index.md
+    - getting-started.md
+    #- quick-tutorial.md
+    - changelog.md
+    - features.md
+    - upgrading.md
+    - troubleshooting.md
+    Policies:
+    - security.md
+    - stability.md
+    - rust-version.md
+    - kubernetes-version.md
+    - release-process.md
+    Third Party:
+    - adopters.md
+    - guides.md
 
 - Controllers:
     Concepts:
@@ -107,6 +109,7 @@ nav:
   - contributing.md
   - website.md
   - tools.md
+  - architecture.md
 
 markdown_extensions:
   - attr_list # https://squidfunk.github.io/mkdocs-material/reference/images/