Add recommended colourmaps to wiki

[manodeep]

There are no recommended colour maps (or at least colourmap style) on the wiki. For displaying continuous quantitative data, we should at least be using perceptually uniform colourmaps, and ideally colourblind-friendly colourmaps like cividis.

[manodeep]

Relevant python package cmasher and the associated JOSS paper that shows the pitfalls of the jet colourmap.