docs(cache): add store-specific config

Signed-off-by: Benjamin Janssens <benji.janssens@gmail.com>

docs/backend-system/core-services/cache.md

@@ -11,27 +11,84 @@ This service lets your plugin interact with a cache. It is bound to your plugin
 
 The cache service can be configured using the `backend.cache` section in your `app-config.yaml`:
 
+### In-Memory (default)
+
 ```yaml
 backend:
   cache:
-    store: redis # or 'valkey', 'memcache', 'memory'
+    store: memory
+```
+
+### Memcache
+
+```yaml
+backend:
+  cache:
+    store: memcache
+    connection: user:pass@cache.example.com:11211
+```
+
+### Redis
+
+```yaml
+backend:
+  cache:
+    store: redis
     connection: redis://localhost:6379
 
-    # Store-specific configuration (Redis/Valkey only)
+    # Store-specific configuration (optional)
     redis:
       client:
-        # Optional: Global namespace prefix for all cache keys
+        # Global namespace prefix for all cache keys
         namespace: 'my-app'
-        # Optional: Separator used between namespace and plugin ID (default: ':')
+        # Separator used between namespace and plugin ID (default: ':')
         keyPrefixSeparator: ':'
         # Other Redis-specific options...
         clearBatchSize: 1000
         useUnlink: false
+```
+
+### Valkey
+
+```yaml
+backend:
+  cache:
+    store: valkey
+    connection: redis://localhost:6379
+
+    # Store-specific configuration (optional)
     valkey:
-      # Optional: Global namespace prefix for all cache keys (including separator used between namespace and plugin ID)
+      # Global namespace prefix for all cache keys (including separator used between namespace and plugin ID)
       keyPrefix: 'my-app:'
 ```
 
+### Infinispan
+
+```yaml
+backend:
+  cache:
+    store: infinispan
+
+    # Store-specific configuration (optional)
+    infinispan:
+      servers:
+        # IP address or hostname of the server (default: '127.0.0.1')
+        - host: 127.0.0.1
+          # Port number of the server (default: '11222')
+          port: 11222
+      # Name of the cache (default: 'cache')
+      cacheName: cache
+      mediaType: application/json
+      authentication:
+        # Whether authentication is enabled (default: 'false')
+        enabled: true
+        userName: yourusername
+        password: yourpassword
+        saslMechanism: PLAIN
+```
+
+A full list of configuration items is available [here](https://docs.jboss.org/infinispan/hotrod-clients/javascript/1.0/apidocs/module-infinispan.html), including support for backup clusters.
+
 ### Namespace Configuration
 
 For Redis and Valkey stores, you can configure a global namespace that will be prefixed to all cache keys:
@@ -40,8 +97,9 @@ For Redis and Valkey stores, you can configure a global namespace that will be p
 - **With namespace**: Cache keys use the format `namespace:pluginId:key` (e.g., `my-app:catalog:some-key`)
 
 For Redis, `keyPrefixSeparator` controls what character is used between the namespace and plugin ID (defaults to `:`).
+For Valkey, you set the full `keyPrefix` including the separator.
 
-**Note**: Memory and Memcache stores do not support namespace configuration and will always use the plugin ID directly.
+**Note**: In-memory, Memcache and Infinispan stores do not support namespace configuration and will always use the plugin ID directly.
 
 ## Using the service