docs(caching.md): add batch redis requests to docs

docs/my-website/docs/proxy/caching.md

@@ -225,6 +225,32 @@ litellm_settings:
     supported_call_types: ["acompletion", "completion", "embedding", "aembedding"] # defaults to all litellm call types
 ```
 
+
+### Turn on `batch_redis_requests` 
+
+**What it does?**
+When a request is made:
+
+- Check if a key starting with `litellm:<hashed_api_key>:<call_type>:` exists in-memory, if no - get the last 100 cached requests for this key and store it
+
+- New requests are stored with this `litellm:..` as the namespace
+
+**Why?**
+Reduce number of redis GET requests. This improved latency by 46% in prod load tests. 
+
+**Usage**
+
+```yaml
+litellm_settings:
+  cache: true
+  cache_params:
+    type: redis
+    ... # remaining redis args (host, port, etc.)
+  callbacks: ["batch_redis_requests"] # 👈 KEY CHANGE!
+```
+
+[**SEE CODE**](https://github.com/BerriAI/litellm/blob/main/litellm/proxy/hooks/batch_redis_get.py)
+
 ### Turn on / off caching per request.  
 
 The proxy support 3 cache-controls: