Add Documentation and Tests for GraphConstructorSpatial

[jernsting]

GraphConstructorSpatial requires a atlas_name_coords.csv. Please provide an example.
Is this constructor intedet for DTI or RestingState data?
Why is the default atlas HO not tested? Why is it not contained in the graph package?

[VHolstein]

• Check license
• Write authors if required
• Update documentation abot DTI and fMRI

[jernsting]

Documentation of atlas is still missing.

[jernsting]

Please also remove warning (untested) from documentation: https://wwu-mmll.github.io/photonai_graph/api/graph_construction/#graphconstructorspatial

[VHolstein]

• Is this constructor intended for DTI or RestingState data? -> Can be used for both DTI and Resting State (already in docs), expanding documentation even further
• Why is default atlas HO not tested -> atlas is tested see test_ho_atlas, can add a second test if needed
• default ho_atlas is contained in tests, comes from ABIDE and is not distributed as part of the package due to a lack of clarity concerning license issues