docs(cache): add note on cache key normalization and escapeKey usage (#632)

Author: mrkaashee

docs/content/docs/2.features/cache.md

@@ -152,6 +152,51 @@ await useStorage('cache').clear('nitro:handlers')
 Read more about Nitro Cache.
 ::
 
+### Normalizing Cache Keys
+
+::important
+**Cache keys are automatically normalized** using an internal utility that removes non-alphanumeric characters such as `/` and `-`. This behavior helps ensure compatibility across various storage backends (e.g., `file systems`, `key-value` stores) that might have restrictions on characters in `keys`, and also prevents potential path traversal vulnerabilities.
+::
+
+For example:
+
+```ts
+getKey: () => '/api/products/sale-items'
+```
+
+Would generate a key like:
+
+```ts
+api/productssaleitems.json
+```
+
+This behavior may result in keys that look different from the original route or identifier.
+
+::tip
+To manually reproduce the same normalized key pattern used by Nitro (e.g., when invalidating cache entries), you can use the `escapeKey` utility function provided below:
+::
+
+```ts
+function escapeKey(key: string | string[]) {
+  return String(key).replace(/\W/g, "");
+}
+```
+
+It's recommended to use `escapeKey()` when invalidating manually using route paths or identifiers to ensure consistency with Nitro's internal key generation.
+
+For example, if your `getKey` function is:
+
+```ts
+getKey: (id: string) => `product/${id}/details`
+```
+
+And you want to invalidate `product/123/details`, you would do:
+
+```ts
+const normalizedKey = escapeKey('product/123/details')
+await useStorage('cache').removeItem(`nitro:functions:getProductDetails:${normalizedKey}.json`)
+```
+
 ## Cache Expiration
 
 As NuxtHub leverages Cloudflare Workers KV to store your cache entries, we leverage the [`expiration` property](https://developers.cloudflare.com/kv/api/write-key-value-pairs/#expiring-keys) of the KV binding to handle the cache expiration.