Fix documentation about `immediate`
Fix documentation about `immediate`

Unless I misimplemented this, "immediate" means persist to ElasticSearch "immediately"; before flushing.  Default behavior is false; persist to ElasticSearch postFlush.
fazland/FazlandElasticaBundle,alekitto/FazlandElasticaBundle,ramuss/FazlandElasticaBundle,alekitto/FazlandElasticaBundle,ramuss/FazlandElasticaBundle,fazland/FazlandElasticaBundle