update readme

README.md

@@ -42,6 +42,7 @@ two subkeys:
 - `primary_key_field` - the name of the field that will be used as the primary key (default: **id**)
 - `ttl_field` - the name of the field that will be used as the ttl field (default: **ttl**)
 - `value_field` - the name of the field that will be used as the value field (default: **value**)
+- `key_prefix` - the prefix used in front of the item keys (default: **null** which means none)
 
 Autogenerated default config (via `bin/console config:dump rikudou_dynamo_db_cache`):
 
@@ -83,6 +84,15 @@ rikudou_dynamo_db_cache:
             # The depth of the JSON parsing for encoding/decoding
             depth:                512
 
+    # Session related configuration
+    session:
+
+        # The ttl for the session, defaults to ini setting session.gc_maxlifetime
+        ttl:                  null
+
+        # The prefix for sessions
+        prefix:               session_
+
     # The field to be used as primary key
     primary_key_field:    id
 
@@ -91,6 +101,9 @@ rikudou_dynamo_db_cache:
 
     # The field to be used as value
     value_field:          value
+
+    # The prefix used in front of keys when storing
+    key_prefix:           null
 ```
 
 ## Usage