start scaffolding getting_started and user_guide

Author: reint-fischer

docs/getting_started/index.md

@@ -5,7 +5,15 @@ Getting started with parcels is easy; here you will find:
 ```{toctree}
 The installation guide <installation.md>
 <!-- - a quickstart tutorial to running your first simulation <../examples_v3/parcels_tutorial.ipynb>
-- an overview of the important concepts <../examples_v3/tutorial_parcels_structure.ipynb>
+- an overview of the important concepts <concepts_overview.md>
 - a simple tutorial on how to analyse the output from your first simulation <../examples_v3/tutorial_output.ipynb> -->
 
 ```
+
+```{note}
+TODO: Write quickstart tutorial. This should focus on getting users familiar with the different steps to take to run a simulation. Implicitly we should introduce them to the important concepts, but it should not be an in depth explanation. Instead we should reference to the concept overview and the reference API
+```
+
+```{note}
+TODO: Rewrite parcels concepts overview. This .md file should contain most of what is currently in the tutorial_parcels_structure notebook.
+```