Add storage backend documentation (#2137)

* Add storage backend documentation

* Add storage patterns documentation for wrapper caching strategies

- Add PassthroughCacheWrapper section for multi-tier caching
- Document TTL clamping strategy for optimized memory usage
- Add example for wrapping custom storage implementations
- Explain how to combine fast in-memory caches with persistent remote stores

* Update docs

docs/docs.json

@@ -107,15 +107,16 @@
                 "group": "Advanced Features",
                 "icon": "stars",
                 "pages": [
-                  "servers/icons",
-                  "servers/context",
-                  "servers/proxy",
                   "servers/composition",
+                  "servers/context",
                   "servers/elicitation",
+                  "servers/icons",
                   "servers/logging",
+                  "servers/middleware",
                   "servers/progress",
+                  "servers/proxy",
                   "servers/sampling",
-                  "servers/middleware"
+                  "servers/storage-backends"
                 ]
               },
               {