Removing indexing tutorial

as new one will come from @michaeldenes

Author: erikvansebille

docs/user_guide/examples/documentation_indexing.ipynb

@@ -45,7 +45,6 @@ examples/tutorial_schism.ipynb
 examples/tutorial_velocityconversion.ipynb
 examples/tutorial_nestedgrids.ipynb
 examples/tutorial_manipulating_field_data.ipynb
-examples/documentation_indexing.ipynb
 ```
 
 ## Create ParticleSets