[FEATURE] add settingsKey when creating the index 

With the settingsKey it is possible to set further
Configuration for the Index by using the alias
[TASK] adding documentation for index settings
Merge pull request #35 from mgoldbeck/indexsettings

[FEATURE] Allow to set Index Settings for the Nodes-Index
Merge pull request #36 from Flowpack/indexsettings

[FEATURE] Allow to set Index Settings for the Nodes-Index