feat: add notes to all applications

src/content/docs/applications/metrics-server.mdx

@@ -13,3 +13,11 @@ hero:
       link: https://gitea.alexlebens.dev/alexlebens/infrastructure/src/branch/main/clusters/cl01tl/helm/metrics-server
       icon: right-arrow
 ---
+
+# Purpose
+
+Core Kubernetes service that provides basic metrics on cpu, memory, and disk that is used by Kubernetes for tooling such as scaling. Also what is seen in [Headlamp](https://docs.alexlebens.dev/applications/headlamp) for live stats.
+
+# Notes
+
+Like some other services, it happily runs in the background without trouble.