docs(cloudflare): minor updates to the caching doc (#180)

Author: vicb

pages/cloudflare/caching.mdx

@@ -425,7 +425,8 @@ export default defineCloudflareConfig({
 
 #### Queue
 
-A queue must be setup for projects using revalidation (either Time based or On-demand).
+A queue must be setup for projects using Time-Based revalidation.
+It is not needed when revalidation is not used nor only On-Demand revalidation is used.
 
 **Configure the queue**
 
@@ -719,6 +720,11 @@ This component can either call the Cache API's purge function directly or route
 
 Cache purge are only called when you call `revalidateTag`, `revalidatePath` or `res.revalidate` in the pages router. It is not called for ISR revalidation.
 
+To use cache purge, you need to define the following wrangler secrets:
+
+- `CACHE_PURGE_API_TOKEN` should be set to [an API token](https://developers.cloudflare.com/fundamentals/api/get-started/create-token/) with the `Cache Purge` permission
+- `CACHE_PURGE_ZONE_ID` should be set to the [zone ID of your deployment domain](https://developers.cloudflare.com/fundamentals/account/find-account-and-zone-ids/)
+
 Below is an example configuration for integrating the cache purge component in your `open-next.config.ts`:
 
 ```ts