Add slack mode documentation

lib/EventStore/Tiny.pm

@@ -247,6 +247,10 @@ Standard constructor. Understands all attributes as arguments. For most use case
 
 A hashref representing the initial state. B<Default: C<{}>>
 
+=item slack
+
+See L</SLACK MODE> below.
+
 =item cache_distance
 
 The number of events after a new snapshot is cached for accellerated access. 0 means the cache is updated after each event. undef means the system does not use any caching. B<Default: 0>
@@ -322,6 +326,10 @@ Returns the internal L<EventStore::Tiny::EventStream> object that stores all con
 
 Returns a cloned copy of the ininitial state all events are applied on, which was defined by L</init_data> as a hashref.
 
+=head2 SLACK MODE
+
+By default, L<EventStore::Tiny> is in strict mode. That means, that all L</snapshot> data is cloned to prevent the internal state from illegal modification. However, if you B<really know what you're doing>, you can activate L</slack> mode to get references to the internal (cached) state. This improves performance a lot, but has also the downside that it can break your data consistence. You really have to make sure, that you modify your data with events only!
+
 =head2 OTHER
 
 =head3 is_correct_snapshot